TRX250R.ORG
Workshop => Engine and Bottom End => Topic started by: countryboy9799 on February 24, 2015, 09:13:05 AM
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I knew this was going to be a project but its getting to be more than what I wanted. Oh well riding for me is still 2 months away. I tested my compression on a somewhat warm engine and it tested out to 110psi. The spark plug was wet but it may have something to do with the carb that randomly overflows. I think the float is hanging up on something in there because it will seal and then later it will overflow.
So should my next step be to get look into new reeds or just do a tear down and see what I have?
Part of me just wants to go with a top end kit from ESR or what do you guys recommend?
I should also add that my main is a stock 152 and it has a FMF Fatty gold series. It really should be running lean according to everything I have read, keep in mind the temps have been 10 to 30F. On a positive note it started on the second kick the other day and normally starts quickly. I have only started it maybe 8 times since I got it.
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I should also add that I want to keep it as close to stock as possible. What I do is mainly trail riding with my family and I want it to be reliable.
Thanks
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I'd start with a leak down even before I'd tear into the motor just in case the crank seal or cases have leaks, and probably rebuild the top end.
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I will start with a leak down test. I took the pipe off and was able to see the piston on the exhaust side and the cylinder in the intake side looking in from the exhaust. It actually didnt look to bad from what I could tell. I couldnt see any scoring or anything so maybe just do a leak down test, if that checks out good take the top end off and put a new piston and/or rings in it. I will have to get one of those this week.
On a side note I dropped my carb and bent the idle speed/choke assembly, I tried to straighten it out and broke it in half. I am not sure if I should find a replacement or just replace the carb as I am having trouble with the float. Anyone have some links for new ones?
There is an exhaust leak where the pipe connects to the engine and where that spacer piece connects to the pipe. I noticed it when it was running and there is oil leaking out pretty good.
Would that cause low compression?
Thanks
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Excessive piston and ring clearance between a the bore, that compression test was done at wot and you kept kicking till the gauge quit rising correct?
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It was wide open and I kicked until it quit rising.
What is the lowest you want it to go before rebuilding?
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i think its below 160psi. and you can get a choke / idle adjuster on e bay last time i seen there about 40$ new
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If you're at 110 psi tear that top-end apart and check it out. No sense in beating around the bush, 110 is extremely low
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Well I got my pressure tester rigged up and it lost pressure quickly, maybe went from 7 lbs to 2 in 30 seconds. I didn't test for other leaks since I can't use soapy water at the temps here are too cold.
I did plug the transmission breather with my thumb and kept pumping it up and when I released my thumb there was a lot of pressure in the transmission so that would mean my crank seals and/or case gasket is shot right?
Anything else I need to do before I start tearing it apart? I have taken a 250r motor apart 25 years ago when I had my first 2 but this will be my first time taking the transmission apart.
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can pull the mag cover and see if there is air on that side and or oil. if the right side seal is leaking bad should have gear oil in the crank case. you can change the seals with out splittin the motor.you will have to remove some stuff but not a bad job.
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Here is what I found on the Mag side. Some antifreeze in the bottom and when I lift up and down on the flywheel there is noticeable play. I then pressurized it again and it leaked down but when I lifted up and down on the flywheel you could hear very clearly the air coming out. I didn't notice any oil in there though. I guess a complete tear down is inevitable now. Do you guys think the bearings are bad or could the cases be bad?
Here are some pics.
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i would just go for a rebuild at this point. there is a coolant leak somewhere head gasket /base gasket . from the looks of that mag either the cover gasket was bad and alot of water got in there to rust it up so bad or there has been a coolant leak for a bit.
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So how does the coolant get from the head/base gasket to the Mag cover? I have never had the lower case apart so I am just trying to understand how it would. It would leak down past the crank bearing and seal? If that's the case the antifreeze would more than likely take the bearing out.
Any tricks to getting the flywheel off? I cant get the nut off because I cant hold the flywheel. I am not sure if oriellys or advanced auto has a flywheel holder for this.
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well to make your life easy with out air tools get a 1\2 electric impact gun i will save you headaches in the long run. you will need a mag puller that threads into the mag once the nut is off i suggest putting some p b blaster on that nut first before breaking it free. if this nut is giving you trouble wait till ya try and remove the clutch basket nut by hand lol.
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The clutch basket was the first thing I did, that was easy except for pressing the gear in the basket lol.
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Well I found the problem of where the play was in the crank on the left side.
The bearing on the left side for the inside diamater is somewhere around 1.075 and 1.085. The crank on that side is around 1.097 to 1.100 which the right side crank is about 1.100. Both bearings are tight in the case so did I dodge a bullet or do I need a new crank? I was hoping the play would be in the bearings themselves but there doesn't seem to be any although the left one does feel rough but the right side feels pretty good.
I never did find where that antifreeze got into the stator case. The only thing I can think of is when I took that drain plug out of the side of the block a few weeks ago drained some in through where the wires go through the stator case.
I measured the piston and cylinder the best I could using a calipers, I know it isn't the best thing to use but its what I have and that tested out at 2.600 which is about 66 MM. Does that mean my bore has never been bored out? That would be great. I plan on taking it somewhere to have it checked and bored if needed. The piston looked really good, no scoring or anything. Just some carbon on top.
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Heres a bunch pics. You can see some wear on the crank where the bearing goes. Any hope for this?
The piston looks like a stock size, there would be a marking on it if it had been bored right?
(http://forums.trx250r.org/vbulletin_imports/1262_4670_2017-04-18_6076.jpg)(http://forums.trx250r.org/vbulletin_imports/1262_4671_2017-04-18_5774.jpg)(http://forums.trx250r.org/vbulletin_imports/1262_4672_2017-04-18_9671.jpg)(http://forums.trx250r.org/vbulletin_imports/1262_4673_2017-04-18_8877.jpg)(http://forums.trx250r.org/vbulletin_imports/1262_4674_2017-04-18_9792.jpg)(http://forums.trx250r.org/vbulletin_imports/1262_4675_2017-04-18_9951.jpg)
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In the last pic it looks like they stripped the threads for the drain plug and is that some form of liquid thread fix or did they weld it?
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Measure the shafts on the crank to see if they are worn or out of tolerance. Pretty sure the right side bearing is a slip fit, left should be an intereference fit. Rough bearings will absolulely give it end play.
Usually there are stamped markings on top of the piston. You can clean the carbon off to to verify.
Hard to see the drain hole, the picture is small on my tablet. The best is to have it kingserted or like. I have ran helicoil solutions on cases without issue, but that is not as good as some of the other insertable threads. Welding is also a solution, but not as insertable threads in my opinion. Welding the cases can be expensive, it will deform them (so they need to be flat plated or machined on the mating surfaces) and it will anneal the aluminum in that area making it a little bit weaker.
Best regards
-Jason
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I cant find the tolerance in the Honda Service Manual I have. Anyone know what it is?
I have 1.100 and looking at a new bearing it specs out as 28MM which is 1.10236. I would think 2 to 4 thousandths of an inch might be a problem for a crank.
I wonder if there is some sort of loctite that I could use to put it together. I have known people that brazed/bronzed shafts that were in pretty bad shape and it worked. This is different though and I want to do it right also. Anyone have a new bearing they could measure the ID?
The threads are ok but it looks like it had been repaired at some point.
I couldn't find any markings so it must be a stock size. Thats one good thing at least!
Thanks
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At this point you have too many things going against you! Start over and buy and replace all bearings and gaskets, have cylinder bored out with new piston kit. Replace old parts with new OEM Honda bearings and gaskets it will be expensive but you will be happier you used and spent on good parts. When all is done re do a pressure check on your motor. Also want you to know if engine leaks thru reeds, exhaust flange, lower cylinder base gasket, spark plug, crank seals, or leak down tester that is all normal. But you should never have to plug or hold transmission breather on leak down test. But f you are leaking from transmission breather or oil drain plug that is clear indication you will have to replace center case gasket!!
Good luck on your build!
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At this point you have too many things going against you! Start over and buy and replace all bearings and gaskets, have cylinder bored out with new piston kit. Replace old parts with new OEM Honda bearings and gaskets it will be expensive but you will be happier you used and spent on good parts. When all is done re do a pressure check on your motor. Also want you to know if engine leaks thru reeds, exhaust flange, lower cylinder base gasket, spark plug, crank seals, or leak down tester that is all normal. But you should never have to plug or hold transmission breather on leak down test. But f you are leaking from transmission breather or oil drain plug that is clear indication you will have to replace center case gasket!!
Good luck on your build!
Not clear indication that center gasket is leaking,more than likely an indication of right side crank seal leaking and using the breather to check for leak was good thinking and the first place I would go.I have never had a center gasket leak ,but have had plenty of right side crank seals leak
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Reason I knew it was not seals leaking was I took engine oil bolt off and there I could hear air I was pumping in coming right out. I then with help figured it out and it was center case gasket. It was pinched and was not sealing properly, after gasket was replaced and new head gasket and bottom cylinder gasket was changed all necessary adjustments made she held pressure. That was the first and hopefully last engine I see with a bad center case gasket.
and let's hope that center case does not leak for anyone. It is a time consuming fix.
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I plan on replacing all the bearings in the transmission and crank bearings along with the crank seals.
I am also going to a cyl. Boring shop to have it measured, it will most likely be bored to the next size.
My only real concern now is the crank, I need to know if the new bearings will be to loose on the crank. I think they will be so what's the next step? Get a hot rods crank or is there a way to salvage mine?
Thanks
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You have almost no way in telling how many hours are on that crank. If the crank is so worn that there is play between the bearing, then it's time for a new crank. The rod on an OEM crank can be rebuilt but not the surface I think you're referring to.
You're best bet would be to get a new crank. Spend the money and do the work now before the crank blows through your cases. It's worth the peace of mind
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They can build that surface back up with flame spraying but is it worth the money probably not with how cheap a hot rods crank is.
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I can get this hot rod crank from amazon and with prime it would be here in 2 days. Is there anything better about the ones from ebay or BDT that run up to 100 dollars more?
http://www.amazon.com/Hot-Rods-4007-Crankshaft/dp/B000FT7E64/ref=sr_1_1?ie=UTF8&qid=1425396187&sr=8-1&keywords=hot+rod+crank+4007#productDetails
I was thinking I may be able to skip the bearing for the shift drum as that feels good and its not like that bearing really turns that much. I will defiantly replace the 4 bearings that those to shafts with the gears sit on. They feel rough and they also turn much faster. Does that sound right?
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I can get this hot rod crank from amazon and with prime it would be here in 2 days. Is there anything better about the ones from ebay or BDT that run up to 100 dollars more?
http://www.amazon.com/Hot-Rods-4007-Crankshaft/dp/B000FT7E64/ref=sr_1_1?ie=UTF8&qid=1425396187&sr=8-1&keywords=hot+rod+crank+4007#productDetails
I was thinking I may be able to skip the bearing for the shift drum as that feels good and its not like that bearing really turns that much. I will defiantly replace the 4 bearings that those to shafts with the gears sit on. They feel rough and they also turn much faster. Does that sound right?
No there isn't anything better about the more expensive crankshaft.
I usually stick to Motosport or Rocky Mountain ATV/MC to purchase items like that. Ebay and Amazon can be iffy for certain products.
Definitely replace the 4 transmission shaft gears. Also look at replacing the 2 counter balancer bearings
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I have ordered a Hot Rod Crank and have the cylinder at a place to be bored. Now all I need to do is order all the gaskets and bearings I need along with any tools if I need any. Just looking for thoughts on whether I need the tools for assembly or I have thought about taking it to the Honda shop. The Honda shop was very good to me the last time I was there, they sold me the flywheel tool for 20 bucks and removed it for me. I know I could have gotten the puller a little cheaper but it was nice to have them remove it since they had an impact wrench.
Just looking for tips and tricks to get it back together without that drive shaft dis/assembly tool.
Thanks
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From what I have saw it looks like cheapcycleparts and hondapartsnation.com have the all the bearings and gaskets that I need at a cheaper price. I emailed cheapcycleparts to see if they were Honda parts and they never responded back to me. Today I called Honda parts nation and they said their bearings were all Authentic Honda parts so I should be good there. Let me know if there is a better place to order bearings.
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I usually check partszilla and honda east toledo...just keep an eye on shipping, that's where they get you!
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I will give Toledo Honda a try, that is where I ordered my water pump off of Ebay. I did end up ordering a crank off Amazon yesterday but I called the 3rd party and made sure the crank was a newer production. They said their stock was out in Nov. and everything was ordered from the factory since then so I should be good. It came in the yellow box which I was told was the better one so I should be good. It was something like $202 so thats even better.
They were only a state away in IA, pretty nice when it comes in 1 day.
(http://forums.trx250r.org/vbulletin_imports/1262_4704_2017-04-18_1675.jpg)
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When you order the main bearings get the '89. They have one more ball.
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Thanks for the help guys, I will order the 89 bearings. Hopefully I can get that order in before I go to work. I got all the bearings out of the case. The only concern I have is the one in the left side for the Main shaft came out quite easily, I just pulled it out with a needle nose after I heated it slightly. I heated the case with a handheld torch and only went to the point of it being to hot to the touch. With the cases started out 15 degrees to begin with it didnt go to bad.
Back to the left side main shaft, should that bearing be tight like the rest to come out?
Also on the left side those 2 screws that retain the bearing for the counter shaft, that's the one where the shaft comes out for the sprocket. I had to use my tool that you pound on to get the screws out, they must have had some good loctite in because I had to turn it 2 turns with that tool. I am going to replace the screws if they are available.
What kind of loctite should I use for those screws? The blue or red?
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Thanks for the help guys, I will order the 89 bearings. Hopefully I can get that order in before I go to work. I got all the bearings out of the case. The only concern I have is the one in the left side for the Main shaft came out quite easily, I just pulled it out with a needle nose after I heated it slightly. I heated the case with a handheld torch and only went to the point of it being to hot to the touch. With the cases started out 15 degrees to begin with it didnt go to bad.
Back to the left side main shaft, should that bearing be tight like the rest to come out?
Also on the left side those 2 screws that retain the bearing for the counter shaft, that's the one where the shaft comes out for the sprocket. I had to use my tool that you pound on to get the screws out, they must have had some good loctite in because I had to turn it 2 turns with that tool. I am going to replace the screws if they are available.
What kind of loctite should I use for those screws? The blue or red?
I don't think that bearing has as much of an interference fit as the others, mine usually pops out with a good amount of heat.
The 2 retaining screws for the countershaft bearing are still available.
Either red or blue loctite will work. I think I used red on mine
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Thanks for the help guys, I will order the 89 bearings. Hopefully I can get that order in before I go to work. I got all the bearings out of the case. The only concern I have is the one in the left side for the Main shaft came out quite easily, I just pulled it out with a needle nose after I heated it slightly. I heated the case with a handheld torch and only went to the point of it being to hot to the touch. With the cases started out 15 degrees to begin with it didnt go to bad.
Back to the left side main shaft, should that bearing be tight like the rest to come out?
Also on the left side those 2 screws that retain the bearing for the counter shaft, that's the one where the shaft comes out for the sprocket. I had to use my tool that you pound on to get the screws out, they must have had some good loctite in because I had to turn it 2 turns with that tool. I am going to replace the screws if they are available.
What kind of loctite should I use for those screws? The blue or red?
The magneto side bearing should have .0003" to .0006" interference fit. The power take off side bearing should have .00020 to .0005" clearance. It is next to impossible to accurately measure anything with calipers and have confidence in your measurements unless you have a set of ring gages to calibrate the calipers when taking inside diameter measurements.
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red loctite has no place in these engines imo. especially bolts that go into the aluminum. someday you may need to remove that reatainer and its likely 1 of 3 things will happen.
1 youll strip the head trying to get the bolt out then youll have a huge problem. a huge problem that can be 100% avoided
2 youll have to hit the impact driver excessively hard and will damage your cases. again a 100% avoidable scenario
3 if you do manage to get the bolt out it may take the case threads with it. yep totally avoidable here also
do as you wish but the blue stuff is more than capable on any fastener of these bikes
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Blue loctite works great!
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I'll get the 89 crank bearings ordered and use the blue loctite. What about the head and base gasket? I thought for the head it was recommended to use the cr250 gasket. Was it thinner for more compression?
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Does cometic make AFM base gaskets for the 250r?
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Does cometic make AFM base gaskets for the 250r?
When you order the main bearings get the '89. They have one more ball.
The 89 trx main bearings are the same as cr500 main bearings?
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When you order the main bearings get the '89. They have one more ball.
The 89 trx & cr500 main bearings are the same?
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Seems like that's what I remember being told by Pete.
Sent from my iPhone using Tapatalk
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Yep, just checked the part numbers on cheap cycle parts & there the same. Good to know, thanks.
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Is this tool worth the money for re installing the crank? I know with the hod rod cranks being tight on the right side I thought it might be a good idea so I don't ruin a crank bearing or crank.
I can add it to my order at Honda of Toledo so it will only be 45 bucks.
Does this thread onto the flywheel side so you can pull the crank into the bearing?
What about the clutch side, can I pull the crank through the bearing on that side?
http://www.ebay.com/itm/NEW-Honda-Driveshaft-Dis-Assembly-Tool-07964-MB00200-/131146273195
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I was told that Mcquire bearing in Portland stocks the bearing not sure of the part number though.
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Is this tool worth the money for re installing the crank? I know with the hod rod cranks being tight on the right side I thought it might be a good idea so I don't ruin a crank bearing or crank.
I can add it to my order at Honda of Toledo so it will only be 45 bucks.
Does this thread onto the flywheel side so you can pull the crank into the bearing?
What about the clutch side, can I pull the crank through the bearing on that side?
http://www.ebay.com/itm/NEW-Honda-Driveshaft-Dis-Assembly-Tool-07964-MB00200-/131146273195
You most definitely want to use a puller to install the crank. I can't see pics of that tool to tell exactly what it does.
I use the Tusk crankshaft puller and case splitter tools when I do my bottom end jobs. They work like a charm and I got them from Rocky Mountain ATV. It works for pulling the crank into the left and right side case halves
However i'd rather have the official Honda tool that's made in Japan. If it's a crank puller then i'd definitely buy it
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https://www.rockymountainatvmc.com/p/989/17166/Tusk-Crank-Puller-Installer-Tool
https://www.rockymountainatvmc.com/p/989/17167/Tusk-Crankcase-Splitter
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Scott, that is only one part for the honda tools needed to pull the crank in.
I posted a honda tool list that is in the faq, and important info section. The honda tools will be pretty expensive compared to the aftermarket setups, of course.
That list will show the other thread adapters, collar adapter and pull bolt needed. If you want to check prices you can run the numbers on the web.
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I am thinking I will just get the Tuck tool. That will pull the crankshaft into the bearings from the flywheel side and clutch side? I dont want to have to purchase 5 different pieces for the Honda brand tool.
Thanks
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What do you guys think of my homemade crankshaft puller? I made it using a 12x1.25 long lug nut welded to a 1/2" coupler. I will use an 1 1/4 steel pipe to but up against the bearing. This is for the flywheel side. On the other side I will use a 10x1.25 wheel stud welded to a coupler.
(http://forums.trx250r.org/vbulletin_imports/1262_4800_2017-04-18_6303.jpg)
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I should be ready to put the cases together this weekend. The only bad thing is when I put my order in at Honda Toledo East I forgot to order the base and head gasket and am trying to get one locally by the weekend. It's frustrating because I was putting in to many hours at work and was rushed when I put my order in. If thats all that goes bad I guess it will be good.
I put the cases together last night without the bearings, seals or gaskets just to see if they were straight and it looks good. There is a very small bit of light that I can see towards the front of the engine where the crank goes but that should seal up with the gasket right?
Looking for tips on where to use the blue loctite. Should I put it on the crank seals when I put them in? I plan on putting some on the retaining screws for the bearings.
The next thing I plan on doing is baking the left case @ 200 degrees for 1 hour, then put the frozen bearings in that side first. My crank is in the freezer now and then I plan on putting the left case back in the oven and hopefully the crank should slip into the left case along with some help of my homemade puller.
I hear mixed results as to taking emery cloth to the right crank bearing to make it more of a slip fit. Thoughts on that?
Thanks
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shouldnt need to go nearly a hour in the oven. 250f for 30min should do the trick. if emory cloth is like scotch brite then i cant see it being very affective against a bearing race but then again ive never tried it
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Emery cloth is like sandpaper.
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My center pawl specs out at .165 and the service limit is .190. The left and right spec out at .195 to .197 so we are good there. I am not finding much out there for the center pawl, a used one on ebay for 50 bucks. Any ideas on where I can get one?
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Its coming together and could have it running today. I was using 1/4" stock thinking I could use that to put the left crank seal in but for some reason it went in to far. Anyone think there will be a problem with it being set in .275? The bad thing is on the bottom it measures .305 and on top its at .260.
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One other question, is my gasket going to be OK? I had the Honda dealer pull the crank into the bearings so I didn't have any problems with that. At first I thought the gasket got twisted but it isn't in there to far and seems to be straight.
(http://forums.trx250r.org/vbulletin_imports/1262_4952_2017-04-18_5178.jpg)
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first rule of thumb, never let a dealer touch your bike. likely it was a high school kid doing the work. the amount of money you payed them you could have bought the tools yourself
the gasket looks sucked in to me, atleast from the pic it looks that way. buy some tools and do it right yourself.
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Actually I have had good luck with this dealer and they didn't charge me much at all. I tried pulling the crankshaft into the first bearing and didn't quite get it all the way. It took the mechanic 10 minutes to fix it.
I just performed a leak down test and that is good now.