TRX250R.ORG
General => Projects => Topic started by: udontknowme on June 01, 2014, 08:56:40 PM
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anybody got plans for new engines this summer ? i got 3 different projects lined up and hopefully ill be able to finish all of em. or atleast 2 of em. heres what i got
1- 300 looong rod. this ones my least priority but i have most of the parts needed so its just a matter getting around to it
2- 548cc that i never could get running quit right last year but i think the head was the problem. pretty sure dome profile was causing the issues. anyways i got a idea to use a smaller bore cylinder that would make it 510cc. it might sound counter productive but im thinking the smaller cylinder might be alittle better design for the particular way im gonna set it up and should nearly be the same power as the bigger one. this ones high on my priority list
3- had a cr500 jug that i did some work on couple years ago and used it last summer then took it off and used a different cylinder. figured i would get this old one back out and do some more work to it and put it back on. not changing the timings much from where they previously were just gonna widen the trans alittle and make the corners more sqaure then recut in the hook angle and do alittle somethin on the exh without making it any higher. left side ive got partially done this weekend
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got alittle more done. still quit a bit to go but its a slow process when you only got a hour or so a day to peck away at it.
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oh ya i should have the 510 cylinder in the next day or so and mock it up to see if it works out like i hope
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got alittle more done. still quit a bit to go but its a slow process when you only got a hour or so a day to peck away at it.
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Wow, that is very nice work. I don't have the tools or skills for that kind of work.
For my summer project I am going to go all the way through my 88, pc frame, new shocks, plastic, a-arms, axle, etc. Also, need to finish up this cylinder for the stroker bottom end and start playing around with pipes to see if I can make it work.
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previously there was some black in the boost port so i think it was pushing exh back in there. alittle extra blowdown should help that
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heres where im at with the intake side
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II've always been curious about how to tell how big to take the ports? I know you can buy the pre made templates but I also know there's a lot of guys who just do it by hand, do you go by hand or use software? I was thinking of messing with some junk cylinders I have from a snowmobile but just don't know how much is too much.
Are you doing anything with the side transfer ports?
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well if you mess with the same engine enough times you should be able to make it faster each time around. especially if you have a dyno and alot of time on your hands. even still its not hard to make the engine faster
im not sure if theres templates for 250r or not. if there is im sure they would work ok for a beginner that hasnt yet learned his own window shapes
i used a computer program on another engine but not the one posted above. the one above i ported it few years ago and just winged it more or less. it ran ok and beat alot of other bikes at the dunes. for a garage job by a amatuer i thought it did pretty good. im just doing alittle more to it now mostly for the hek of it. i dont think any program can ever give you 100% answers but i think they can get you going in the right direction with time*areas and stuff like that and some people have good results using programs. if your asking about the front transfers ya ill do something there but i dont know what yet. ill get some photos when i get that far.
i have no real experience with snomo engines but you might get the timings and widths and see if someone around here can give you a general idea which direction to go
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I figure I'll get some practice at least cleaning up the intake and exhaust ports. May not be as much gain as you can get but just having smoother air flow will help some.
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if its your first time i would probly recomend practicing on something else atleast for a few days just incase you dont want to screw something on your own stuff. theres alot of junk cylinders on ebay for cheap. yz250 for $68 right now but im sure theres 100 different kinds
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I got some junk cylinders to practice on. I did a little bit on one a while back. I also fix a lot of people's junk so cylinders aren't hard to come by.
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i have bought 3 250R this year (replacing 2 I had stolen and one i sold). the 89 I need to do a swap back to a thumb throttle and get it ready to give to my dad. the LSR needs the propeg welding and some carb work. the 88 baja one, just needs some more tuning on the 35AS carb, its already good to go
also taking MSF moto school and buying a Vulcan 500 to ride with my friends.
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i had been using vf3 but theres a few things i dont like about it so im going back to a modified honda cage atleast for now. i think the vf3 was designed for one of the cp cylinders and since it used the cr5 bolt pattern mototassinari also sold it as a direct fit to the cr5 engines rather than design a new unit. kill 2 birds with one stone is what im thinking their logic was
since ill put the honda cage back in i had this idea to fill in some of the space behind the cage. whether it makes any difference one way or the other who knows but ill give it a shot. the slots are nothing more than pockets for the reed screws incase someone dont know
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Vf reeds aren't my favorite. I prefer boysen myself, don't know if they make em for the trx.
For some reason vf reeds on EFI sleds you have to crack the throttle a bit to get em to start.
Another thing that I don't care for about reeds in general is unless you are heavily modded they aren't worth jack.
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i think the vf concept is good but the v3 dont fit for crap on the cr5. got v4 on my other bike and they seem to work good
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hey guys i started on the front trans yesterday. thats all thats left then put it together and try it. i have another cylinder with similar front slanted port so im using that as a guide how to shape the inside of the tunell
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Wow, way to make use of all that room in there!
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ill probly angle it back alittle more but i think its not far off from where it needs to be
(http://forums.trx250r.org/vbulletin_imports/146_2424_2017-04-18_1527.jpg)
(http://forums.trx250r.org/vbulletin_imports/146_2426_2017-04-18_3033.jpg)
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ill probly angle it back alittle more but i think its not far off from where it needs to be
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hey guys this cylinder for my other engine showed up and i think its gonna work like a charm. what i currently have going is a 92x82 but the damn thing has a goofy piston design so it leaves a short circuit hole at tdc which prevents the aux port from being made very large. since im already using a honda rod i got a idea to see how a 89mm borex80mm stroke cylinder looks on the 82mm lower end. the honda piston has a few mm lower wristpin height than the ktm so i throw on a spacer plate i had laying around to roughly compensate for the pin difference just to see what everything looks like. honda piston fits right in like it was meant to be there and fully covers the aux windows plus it will conect right up with the honda rod thats already in there. i wish i would of thought about this before i spent any time fooling with the 92mm cylinder
heres the underneath with both pistons. you can see where the escape hole is on the ktm piston
ktm piston
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honda piston
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i drew lines marking the side skirt at tdc of each piston. blue is the honda and red is ktm. i added the green circle to show how much larger the aux ports can be in the lower portion with the honda piston which is a good thing and i cant wait to see how this thing turns out
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couple pics of the pistons differences
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i dont know what the original timings were when the 89mm cylinder was on the 80stroke crank but with the 82mm stroke and the random spacer i put in it ended up 190/130. so ill make some various thickness spacers and gaskets so i can mix and match to get it at a good starting point. probly lower the timing alittle so if i want to use any upward angle on the transfers i can because right now they enter the bore pretty flat around 7* i think and no way to put any up angle on em with out raising the timing. exh will be plenty low enough i can raise it where ever i need to. i think im gonna try and keep the exh kinda low probly low to mid 190's and just under 70% then make them aux huge and wide as hell. that should give me alot of blowdown and not ruduce the powerstroke to much
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moved the front angles back alittle and traced where everything runs into the bore. i think it should work ok
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ordered piston and headgasket and couple other small things. hope to fire up this turd bucket by the weekend and see if its a complete failure or not :thinking: :jumping0041:
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well since im waiting for the piston figure i just as well do some work on the reed block. had good luck in the past removing dividers on other oe reed blocks so ill try it on this one. was looking at another oe block i had laying around from ktm and the rectangle holes in the block are nearly the same size as the open size of the petal and wondered why the honda rectangle hole is quit a bit smaller than the petal opening. never tried this before but i made the block hole 2mm longer. then had boyesen make some 2 petal reeds
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hey guys i got this together and ran it last weekend but it has some problems. most of the torq seems to be too high in the rpm range. for flat drags i think it would be ok but i ride more on steeper hills that can have a tendency to pull the rpm down and if the torq isnt there your screwed. port timing might be a bit high is what im thinking. started working on another cylinder today that should work better
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well its back together with different cylinder different porting. i think it will work alot better below the powerband. ran it in the garage for min but wont be able to ride until friday. a while back i had a idea what would happen if the reeds could open farther. thought of a simple answer how to do it with a spacer under the stopper. im not sure yet how well it will work but theres only one way to find out. ill test it out probly within the next few weeks
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I don't even use the petal stops.
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did you notice it run better ? ive heard the petal should lift approx .3 x the free length. which is about the same as what the simulators say that ive seen. problem is im not sure you can get these reeds to lift 11mm. might hit the floor and roof but i havent really checked. maybe theres not enough pressure differential to even pull em open that far anyways. alot of questions and hardly any answers
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IMO, Bad idea not to use any stop at all (or spacer). Bend the tips of the stop out to your spec, trim the stop ends back some if it's hitting roof, I'd set them to 10mm. Your reed mod looks alot like the very first billet V-force. and they work super.
It looks like your running a single reed. I'd fab up a extra tension reed and see if you get some TQ back into your motor. Dig up some used reed pedals, cut them down to 1/3 length and lay them on top of the reed pedal you run now. Run it and see if it helps. Cut them back more to add rpm, retest.
Very nice work by the way
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well since im waiting for the piston figure i just as well do some work on the reed block. had good luck in the past removing dividers on other oe reed blocks so ill try it on this one. was looking at another oe block i had laying around from ktm and the rectangle holes in the block are nearly the same size as the open size of the petal and wondered why the honda rectangle hole is quit a bit smaller than the petal opening. never tried this before but i made the block hole 2mm longer. then had boyesen make some 2 petal reeds
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What thickness petal are you using in the last picture? Are those TDR reed petals?
I have make similar reed cage modifications in the past, but had problems with the petals cracking in the middle because the petals are trying to fold inward during the compression phase of the crank case. The petals trying to fold inward, would also ware the rubber coating off of the sealing surface due to the petal abrasion as the petals were deflecting inward on the large cage window.
When I made petals thick enough (.022" to .025" thick) that they would not fail, but were too stiff. Low and mid range power suffered with the thicker petals. I think the petals that ran the best were around .016 to .018" thick, but would fail.
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theyre just boyesen reeds. .020" thick. i thought about trying some carbon fiber but i think they might be thinner and probly not a good idea on a large petal . i could image a thin petal (under .020") buckling if its surface area is too large without enough support from center dividers, although ive used .020" boyesens on other blocks and havent noticed the center folding inwards so maybe .020" is just barely strong enough. plus i was thinking a very large super thin petal may not do well at high rpm if it has to lift a large distance. vf cages seem to do well with very thin carbon petals but it seems like they only have to lift a short distance during each cycle
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i got the cage out and put the spacers under the stoppers and the cage is back in. end of the week ill have a answer wether it does any good or not. at this point i dont see how it couldnt do some good. 7mm lift seems very small. ktm is 10mm lift without any modification although the cage is wider and not as tall so that probly factors in. not able to use epoxy on this cylinder because the cage barely fits in the intake with the spacers but i keep seeing large amounts of fuel collecting at the back of the intake and that was the reason i had tried the epoxy last time. seemed like if some of the hiding spots were eliminated it might do some good.
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My last time at the Dyno testing the arctic cat/saber/liger reeds I tried the VF3 early and late versions.
the Early version is a 4pedal design(16total) and comes with reed stops and a removable stuffer
the Later version is a 3 pedal design(12total) and comes with a molded in stuffer and no reed stops
i was told along time ago that the Early version was the one to have and Not to run the stuffer. Many people do not run them in the sleds and when I picked up a used set they had been removed, so I was not able to make a test with and without them.
So what I found was the Early VF3 unmodified but with no stuffer made the same HP as the Late Vforce 3
I then heated and bent the plastic reed stops on the Early VF3 so that when installed back into the cylinder they actually rubbed top and bottom of the intake track.
Power went up 1 HP at peak so getting excited I decided to remove the stops ( I left about 1/4 of it still on because I crudely cut them while at the Dyno and did not want to hit the pedals with the cut off wheel )
well power went dropped back down 1 hp to being equal to the stock VF3 early and late models
All in all I seen less than a 1% change in my testing since the bike made only 1 hp more in a 110hp motor
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if it does any good im thinking it will be small like you were saying. hell it might not even be noticable. probly have better results changing out the small stinger to a bigger one. i did find out one thing for sure though. that last cylinder didnt pull worth a shit below the pipe. after i reported a new one it pulls million times better below the pipe and doesnt seem to have lost much off the topend. not as much as i figured it would anyways. the timings are still somewhat low so i can make changes later on
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With the spacer under the stopper, it moves the flex point to one spot, that edge. That effect on the reed will feel like the stopper is removed and is just hitting the roof. Not sure if thats the way to go for power or reed life (hasn't worked for me anyway).
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since every engine is alittle different i try not to assume a particular modification will or wont work on all engines before its even tested. its best to just try it and see what happens. atleast thats my thoughts anyways. its simple to take the spacers back out if theres nothing to be gained
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Good point. Just throwing out some stuff to help.
The mod will work (add gap), but no reed is happy flexing on a edge back at the screws, on any motor.
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I agree with doc that there better approch would have been to have put more bend in the stoppers for reed life
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if it does any good im thinking it will be small like you were saying. hell it might not even be noticable. probly have better results changing out the small stinger to a bigger one. i did find out one thing for sure though. that last cylinder didnt pull worth a shit below the pipe. after i reported a new one it pulls million times better below the pipe and doesnt seem to have lost much off the topend. not as much as i figured it would anyways. the timings are still somewhat low so i can make changes later on
Many of the Honda CR had back stops that were shaped in a manner to simulate a spacer strip between a conventional stop that had the curvature of the back stop tangent with the clamping area.
The theory was to allow the initial (low lift) tension of the petal to be low and then the tension increased as the petal made contact with the curvature of the back stop. I never saw any abnormal petal failures on the OEM Honda reeds that had this feature. I saw a lot of failures with some of the aftermarket reed petal kits that had too thick of a spacer strip.
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Different types of reed petals and reed block do have an influence on the shape of the power curve but not as much as most guys are expecting. Most of the time you cannot feel the difference between different reed configurations, but the dyno will show these small differences.
The shape of the power curve is primarily controlled by the pipe and porting combination, not the reed valve configuration, unless the petals are floating at high RPMs or the petals are so stiff they will not open enough to provide the necessary flow.
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Are v2 better than v3. I see a lot of v3 users, not v2?
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Many of the Honda CR had back stops that were shaped in a manner to simulate a spacer strip between a conventional stop that had the curvature of the back stop tangent with the clamping area.
The theory was to allow the initial (low lift) tension of the petal to be low and then the tension increased as the petal made contact with the curvature of the back stop. I never saw any abnormal petal failures on the OEM Honda reeds that had this feature. I saw a lot of failures with some of the aftermarket reed petal kits that had too thick of a spacer strip.
i assume you meen something like the oe cr500 stoppers. it has has a step near the front where it screws onto the cage. if my thinking is correct this would simulate a spacer being under the stopper and probly allow the very front of the petal to lift slightly more than if it were using standard continious arc stoppers
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ive thought about this spacer idea numerous times lately. looked it over 100 times. even with the spacer, the reed still seems to bend at a fairly gradual arc near the front where its screwed onto the cage. even if you look at the pics you can see it doesnt kink the petal. now if there were 2 spacers installed i could definatly see it trying to kink near the front. thats the great thing about forums with sharp people. you can get more sets of eyes seeing stuff you may have over looked.
i know alot of guys dont believe in simulators and i dont consider them the final word either but i think they can be another good tool to use along the way. my ktm reed block was showing very good results lifting the reeds 2mm more on the sim although i havent got around to messing with it yet. i know this aint the ktm and the cage is completely different in dimension but still i think the cr5 petals are underlifted. when you look at every aspect of the stock engine it screams longevity, not performance.
i did fire the engine the other day after i installed the cage with spacers. sounded good. but wether it runs well is another matter. ill have some kind of a answer over the weekend and report back what i find
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hey guys i had a chance to test it today. same spot same weather. now i would never say it added 5horse but the engine for sure pulls stronger than it did last weekend. pay no mind to the launch :glee: theres no swinger extensions so you just ride the clutch and try to keep it going straight
[video=youtube;0cJMdUWo4AY]https://www.youtube.com/watch?v=0cJMdUWo4AY&feature=youtu.be[/video]
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what do you make of this plug ? about 2/3 of it has 1.5mm ring then a small section is thicker lick 2.5mm. i wonder if thats from idling it to turn the bike around ? ive seen this before on other plugs where the ring isnt consistent in size all the way around but couldnt figure out what caused it. the burned part of the strap appears to be bewteen the red marks
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