TRX250R.ORG
Workshop => Engine and Bottom End => Topic started by: PORTED R on May 26, 2014, 11:00:02 PM
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Motor is twisting upward in the frame ,busting my front motor mount loose all day
Ran good all day then the waterpump started leaking and clutch cover started leaking tranny oil
So new wp and clutch cover gasket is in order
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If the chain is to tight it can be hard on motor mounts and when I say to tight Im talking about when rear suspension is compressed enough that the centerline of countershaft,swingarm pivot and axle are all in line with each other, that is when the chain will be its tightest
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How about if theres no head stay bolt
If I'm sitting at the line and I look down and rev the piss out of it I can see the motor twist
Nate did say it would be a hard running pv 370 haha
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If I'm sitting at the line and I look down and rev the piss out of it I can see the motor twist
The motor twists without any load applied? Hope those are not my motor mounts you are breaking!
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The motor twists without any load applied? Hope those are not my motor mounts you are breaking!
No pumashine mounts yet
It's crazy its like watching a built car motor twist in the chassis
And its doesn't help I got a out of frame pipe ,I don't want to crack it
I'm gonna slap a headstay bolt in and see wat it does
All other motor mount bolts are nylon nuts
But the front mount keeps coming loose
Anybody else with a 370 experience a little extra vibrate threw your handlebars
Counter balancer sounds good ,no weird noise ,plus I just got it from Nate McCoy a few months back
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What size piston are you running? Is it a stock CB?
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since the crankshaft spins paralell with the bike it couldnt twist sideways like a car when it revs up . if the engine is moving then obviously some mounts are probly broke or the case bolt holes are wallered out
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The motor is twisting up towards the gastank
Not side to side ,should of mentioned that
The only motor mount coming loose is the very front one
The bottom ,and two back ones stay tight
I wasn't running a head stay bolt either
Piston is a fresh 79mm
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Cb is stock
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How about if theres no head stay bolt
If I'm sitting at the line and I look down and rev the piss out of it I can see the motor twist
Nate did say it would be a hard running pv 370 haha
never seen that before, but I have not owned a 370 before either
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Do you notice flex in the frame or any of the mounts? Have a helper blip the throttle so you can check it out closely. I wouldn't think the engine should be able to move very much if any at all. If it does you may need to add some gussets.
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Ok so I I went out in my garage I pulled out each motor mount bolt out one at a time
Case holes aren't wallered
Bolts them self are fine ,I Mic'd and compared to another set of motor mount bolts I had laying around ,and all the same
But even if the holes were warped or bad bolts ,the case I'D holes are still larger then the OEM case bolt OD
So there's still wiggle room for everything to move up and down but not side to side
The only mount I'm having trouble with is my front mount
I had my bro blip the the throttle for me and the only one that flexed was the front
Case holes are good ,mount holes good
I have seen some horrible engine mounts and holes before on a car and mine being 20+ years old are good shape
I'm thinking because I didn't have a head stay on there's too much flex on top
I'm gonna pull the cb out some time soon and check it
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why dont you have a head mount ? seems crazy not to
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why dont you have a head mount ? seems crazy not to
All the fast guys don't use them out here...ha
There's just a lot of people out here in the drag world that don't use them
They just run a head stay with no bolt ,supposed to let the motor rev higher
I have a headstay on it ,but no bolt
After watching the motor move like that in the chassis ,I'm skeptical about running the frame
I didn't have this problem when I had a 310 in it ,but once I slapped the 370 in its been fighting me
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I've never had a headstay on my 370 and I've never had a problem with it moving. I have broken the lower mount a couple times but that's it. I double plated it and it hasn't broken anymore
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I just don't know
I'm thinking I have to take the motor out and see if the frame is bent anywhere
I did notice the bottom mount was a little off on the right side ,I had to push the motor forward to get the bolt all the way threw on the right side
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I'm gonna pull the cb out some time soon and check it
That is what I was gonna suggest. A lightened CB or one that is off by a tooth will cause the bike to shrug when revved. I have broken all the motor mounts due to CB issues
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I would be thinking it's either the CB or weak or cracked frame.
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I would be thinking it's either the CB or weak or cracked frame.
That's what I'm thinking aswill
Frame is pretty beat up ,its had like 3 or 4 motors in it
Bought it from a guy that rode it hard
Or its the CB alignment or old cb bearings
If cb looks fine and is aligned I'm pretty sure I'm gonna junk the frame
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If it is moving that much and you put a head stay bolt in I bet you will be cracking stuff fairly soon. No head stay bolt here either. I would check the CB.
And where the heck were you running at? Should of came to the beach.
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If it is moving that much and you put a head stay bolt in I bet you will be cracking stuff fairly soon. No head stay bolt here either. I would check the CB.
And where the heck were you running at? Should of came to the beach.
I found some sand out in a field my cousins ride ,decided to run it for a bit
Ya gonna pop the cover off today and check the CB and alignment
Also check the frame for cracks ,I'm thinking this frame has seen better days
I can get all the motor mounts super tight and that motor well twist itself free
Never seen that before
I ain't gonna fire it up in tell I get it figured out
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Had similar issues with front mounts. Ended up being frame just slightly cracked out in several places. Lined everything back up and made thicker aluminum front mounts. Running top mount still though but hasn't messed up since at about 3 years. I blame it on McCoy as well haha
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I just built 1/4 inch mounts for my 89, and then put lower rear mounts in too. Now crossing my fingers that the frame holds up
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Quick update
I got some good daylight ,took a better look at my mounts
The bottom mount and front mount are tweaked to the left about 1/8th of a inch maybe a little more but not much
I still havent checked the CB ,going to do that tonight
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Sounds like you might have a crank out of true, counter balancer not timed right or either it has a cut counter balancer so the engine will rev up fast.
250R engines dont normally vibe that much even with a big bore, so I would look for something wrong on the engine.
When your sitting still & rev the engine, will the front of the quad drop down real quick like somebody pushing down on the front bumper ?.
Neil
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Sounds like you might have a crank out of true, counter balancer not timed right or either it has a cut counter balancer so the engine will rev up fast.
250R engines dont normally vibe that much even with a big bore, so I would look for something wrong on the engine.
When your sitting still & rev the engine, will the front of the quad drop down real quick like somebody pushing down on the front bumper ?.
Neil
Neil
The crank is a 5mill OEM trued and welded crank
I sent the crank to McCoy and he installed it
I've checked if I had play in my crank bearing already by grabbing the flywheel
When revved real high the back end would squat
Not a lot ,just noticeable to a sharp eye ,but I've had many 250r's do that
Keep in mind ,I haven't checked my CB yet ,been busy
Hopefully pull it tonight
Also I've noticed my frame is tweaked at the bottom and front mount by 1/8 inch or a little more
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This motor with a stock ignition and Out of frame pipe revs really high and fast ,almost like a built 310 with a short rod
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UPDATE!!!!!!!!
OK I pulled the clutch cover
Balancer was aligned with primary gear
But I found about 1/8th inch of play in the bearing
It rolls smoothly but has play
What do u guys think
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Check the cb bore in the cases, I have found when the cb bearing gets loose the cb starts to beat the cases, loosening tolerances and causing excessive vibration.
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I think I caught it just in time
Case bores look good
Balancer itself looks perfect but bearing has in and out play and up down
Looks like I'm looking for a counter balancer with a good bearing for sale
Never ending on these motors
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Give me a call, there is a couple people in town that will rebuild your cb,
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Ok
Will do