uhoh bad cylinder

[john willhoite]

noticed it was sounding kind of funny.
compression was low.

cylinder and piston are toast.

Hope to have it all back together for the race next weekend.

[QuadJunkies]

eeeww.... feel your pain. Hopefully ours does better this time around .

[vondeister]

John,

ouch.....

[john willhoite]

ready to be back in business

[john willhoite]

got it all back together and snap.....valve is broke, and beat up my brand new piston.

What generally causes a valve to break?

[leager-n-ky]

were you 100% sure on your timing? if the timing was off it could happen

[QuadJunkies]

Originally posted by leager-n-ky
were you 100% sure on your timing? if the timing was off it could happen


Id bet money thats what it was .

[vondeister]

double ouch....

[john willhoite]

At first I had it at 100% where it was.
It was making a wierd clacking under load.

We moved the timing 1 tooth back and got the break.

On the timing mark it lines up in the vallye before the tooth or the valleyafter the tooth.

We missed our first race this weekend.

Trying to make a back up plan.
Should I build another Raptor?
Should i get a backup motor?
Buy a used raptor?
Build a Honda 300ex?

[QuadJunkies]

Originally posted by john willhoite
At first I had it at 100% where it was.
It was making a wierd clacking under load.

We moved the timing 1 tooth back and got the break.

On the timing mark it lines up in the vallye before the tooth or the valleyafter the tooth.

We missed our first race this weekend.

Trying to make a back up plan.
Should I build another Raptor?
Should i get a backup motor?
Buy a used raptor?
Build a Honda 300ex?

You want honesty??

Id go with a 300 ex :o

IF theres anything we can do to help troubleshoot it ,let me know and Ill send you my phone number ;)

[john willhoite]

Honesty......man, the truth hurts!

[rageatvsupermom]

Wow..that does not look good...sorry you missed your race...
what piston did you put in it....are you sure you had enough
clearance?

[john willhoite]

I put the same piston back in.

our valve end clearance was right.

We did not check the squish, assumed it would be the same.

But everything hand cranked just fine. It also sounded good until it was under a load.

I am having a guy trying to regrind the valve seats today. He said it looked like it was going to have to have a new seat put in.
(which he could not do)

Should know latter today.

We have back to back races this time so trying to get ready for this weekend.

[rageatvsupermom]

Ummmm....you got a new cylinder but used the used piston? Did you put new rings on it? If you have to repalce the seat then the head is most likley ruined.....I called you today but no answer. I am sorry you missed a race but we could have rebuilt it if you would have brought us the bike/motor. Good luck...let me know
if we can be of help.

Michele

[john willhoite]

the same, as in same exact specs but brand new, not the old one.
So it was new rings as well.

The cylinder was not new. It was sent to the plater with the new piston for fitting.

[mxdad423]

Ok first let me say I strongly disagee with going with the 300ex will solve your problems, come on people these are race machines, they all break......I can show you 300ex engines straight from the builder that ran like poop and had MAJOR issues, (a very reprible engine builder I add). Constant timing chain stretching causing major issues, timing chain tensioners going bad and causing major issues, ect ect. JMO and what I have experienced with them.Second, from what I can see in your pic, I really don't think 1 tooth off either way, (if it was) would of broke the valve like that, to me it looks like a clearance issue, or valve keeper issue. Did you check all of your specs on the piston before going back togeather? I know you said you didn't check the squish but just wondering if you mic'ed the pison dimension's at all. Did you mic your thickness's of you base and head gaskets to make sure they were the same, remember, a thinner base or head gasket is going to tighten up your valve clearance. When you first tried to start it did the engine seem to buck at all or did it start smoothly?
I am wondering if your keepers on your valve came out and let the valve drop, did you mess with the valves or spring at all before you went back togeather, I always check the keepers on the valves before reassembling any engine, if the keepers pop loose this is what can happen, not saying thats what happened but just saying it could of. I hope you figure out what happened, I think your going to find out it was something really stupid like the keepers, If it were me, I would stay with the Raptor, and buy a back up engine,let me add I would do the same thing if I were running a 300ex. These machines are just a good a the 300ex and are going to be better very soon, IMO.

Kevin Smitley

[QuadJunkies]

To each there own but I just might change my mind on the quad if I could . We mainly chose it for the size and never been a Yamaha fan .lol
So far we have been Ok with it aside of a few things .True all quads that are raced will have there fair share of problems but the frames are total garbage on the 250 -period. I know on our side of the Coast with the long desert races they are not holding up so well - to where the 300 seems to have held up much better.The 250 does not tolerate heat well and finding a better solution on cooling them down is imperative.
Weve had many quads and these wee ones are the biggest PITA's and Im sure a few will agree on that .
My first race quad was a 300ex and it held rock solid. I like the fact they are lighter too, but maybe they are just a tad TOO light??
We still have a long ways to go and learn on these lil rippers .

We have been in the racing scene for many years now and after leaving the mini scene we were really looking forward to a break from break downs every race . The sad thing is the frames are more sad than the minis .:p

As with any quad and racing , if its within your budget to have two quads ,by all means -do it ! Where I have two rippers racing thats not within my budget so we make sure with what we have .We hope that the 250 only improves over time and is a great size of quad for the youth rider who needs to graduate.Im not a total hater, I just can see room for improvments. Being that the average joe for the quad was suited for recreational purposes, dont know that it will happen .
BTW... IVe done a story on the 250 that should be out soon. :)

I am however very greatful to race companies who have done R&D to help make improvements in performance and suspension.

We love having Dee around to call when Troy has a question ! :D
Speaking of ... Ill have to give him a buzz and let him know about a project were working on .;)

[john willhoite]

I think wishing for a 300ex might be on of the "grass is greener on the other side" type of thing.

I did not mic the new or the newer piston.

We did take the head completly apart to do some cleaning of the ports.

I wonder myself if we got it back together complety correct.

the keepers were still on, the spring side of the vavles were all intact.

There was no base gasket, and the head gasket was the identical one. However we did not measure the head to valve clearance.

It started and reved perfectly.
The first time it was making a claking under load. We took it apart put it back together with the timing change started and reved good. Took it out and rode it, was making bad clicking like the valve werent gapped right and then snap. I Shut down immedietly. tryed to start it and knew something was up.

Anyways, got it back together, used the base gasket that came in the kit. (thinking more clearance) Forgot the new sparkplug at home (the broke valve broke the spark plug) So will let you know what happens tomorrow.

This is a high strung high compression engine.

I am only attempting the work because of time and logistic constraints.

I also admit to not being a mechanic.
(but it is fun to pretend, and I am getting good at getting the top end changed,.....well that is if it ever works!)

[john willhoite]

Oh yeah the head guy said the seats ground fine.
And he put in the new stainless steel kibble white valves and titanium keepers.

[QuadJunkies]

Good luck john ! I hope you get it figured out .no fun wrenching when were all supposed to be riding ! ;)

[john willhoite]

Well, fired right up sounds real good.

Put it through a couple of heat cycles.
Negatives:
My compression is only at 150 was at 180
(maybe thats a good thing)
Maybe a slight noise pinned in 3rd gear.

Will let the kid do some gentle riding on it tonight.

[QuadJunkies]

Thats alot of compression lost. Maybe you have a leaking valve ..?
Maybe compression will go up once its broke in again, but I would check valves .
Hope you make your race in time ! I totally know how that goes :scary:

[quadracer707]

Originally posted by john willhoite
Well, fired right up sounds real good.

Put it through a couple of heat cycles.
Negatives:
My compression is only at 150 was at 180
(maybe thats a good thing)
Maybe a slight noise pinned in 3rd gear.

Will let the kid do some gentle riding on it tonight.

John were are you located at??

[mxdad423]

Yea your right they do have their con's just like all the others, I have not had very good luck with the 300 or 400ex, I have done work on alot of them and they just never seem to last, especially after you start going bigger on the bore size, but I guess that holds true with any of the AC motors, once you start punching them out they just can't get rid of the heat quick enough. Another big problem I have had with them like I mentioned eariler is timeing chains and timing chain tensioners, seem to be an on going issue with them. I do agree that the 250 could have a little beefier frame, I do think they dropped the ball on that one, we installed the Teixeria gussett kit on ours so I'm hoping that helps it out. We don't run real long motos like you guys so I don't think the heat thing will be an issue for us, our moto's probably only range from 5 to 10 min, so I think we will be ok there, I hope anyway, LOL....We are still running a stock engine till next year so I guess I will have to let you know next year after we go to a built engine. This being his first year on a big quad I didn't want to build the engine until he shows me he's ready for more, these little Raptys run pretty da*n good in stock form with just an exhaust, but from what he has showed me these first 5 races he will be ready for the engine next season so quit scarrin me with all these horror stories, LOL.

Well John, hope everything is good, I would definatley check to make sure your valves are seating all the way, if they are sticking open just a little that could definatley be your compression loss, did you lap the valves in before you re-assembled it, if not that could be your problem. Good Luck and hope you make it on time.

Kevin Smitley

[john willhoite]

The good news is that it is running good enough to race. I might have a small oil leak somewhere!?!?!? but it could be some leftover from taking the top end off 5 times

How can i tell if the valves ar sticking open? or not closing all the way? We did lap them when we did the head the first time.
The 2nd time I am assuming the guy that ground the seats and put the valves in checked everything.

The frame and battery box have been our only trouble.

This motor ran stock for all sason without me touching it.
As it is now it has a big bore kit and 13.5 piston and made it 20hrs.

So I will let you know if we make it through practice and 4 motos this weekend.

I live in Oklahoma for whoever asked and we race the TQRA series.
See Ya.

[john willhoite]

Figured it out
the clacking on the top end was blowing out the head gasket

torqued it down more and made it through practice

[john willhoite]

Well the story is ending good.

Sent the bike home with my enginge guy and of course he got it runing perfect.

So this weekend we go the holeshot in one class and a best ever 3rd place in the Youth/Coed class.