took my cyliners off and found my sled got a little hot and sezed up. and one piston has a hole that is starting to bore in it. what would be causing this?
piston issues
- Thread starter Danzick
- Start date
I assume it's your 04 Rev? Do a search for "detonation" and another one for "carb boots"
That would be my first guess.
That would be my first guess.
A
Arctic Thunder
Well-known member
X2 on the carb boots. They may look good when you look at them in the sled. But pull them off and move them around a little bit. A couple of my buddies had the same issue. Looked great on the sled. But after pulling them out and really looking at them they have cracks that will open up as the motor moves around in the chassis.
Could be detonation with your head. But if you have a melted hole in the center it is lean. Again Carb boots. Or just jetted to lean with your mods.
Thunder
are you using the correct spark plugs
that can be a problem on all the 800 motors
standard br9es will cause damage
was there any other signs of it being lean
piston wash on exhaust side of cyclinder and piston
I would have a engine leakdown test done
sounds like you have a seal leak
could be as easy as carb boots but could be crank seals
Did the hole get burned all the way through ?
If so you could have stuff in places you dont want it
that can be a problem on all the 800 motors
standard br9es will cause damage
was there any other signs of it being lean
piston wash on exhaust side of cyclinder and piston
I would have a engine leakdown test done
sounds like you have a seal leak
could be as easy as carb boots but could be crank seals
Did the hole get burned all the way through ?
If so you could have stuff in places you dont want it
is the hole starting to bore under the ring on the exhaust side. carb boot delam and also my airbox fell off one cylinder and did the same thing
the dent is right pretty much in the center of the piston and its not through yet but lookes like its gettin close. and the top of the head has some dings in it. had a mechanic tell me the pieces comin out from detination are bouncing around. he said it might be pinging from the dents in the head. gonna check the boots. get back to you guys tonight. thanks.
M
mxracer328
ACCOUNT CLOSED
dont mean to thread jack, but ive had detonation problems too and am wonder what plugs everyone is running
have you checked your jetting i see you have some mods done. i thought in a old post that you stated you where running stock jetting
IM not real sure what the jetting is. gonna look tomorrow night. i cant remember. was planning on going atleast 2 sizes bigger just for save. heres the piston and my head.
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br9ecs
Pulled my jets out and they are 380's. Is this too lean? What is everyone else running? And i am riding around 6000 and above
sea level is 430 pto
420 mag
needle 20 thousandths
20-22.5 pilot
this is just pipe and can no head like you have
420 mag
needle 20 thousandths
20-22.5 pilot
this is just pipe and can no head like you have
I think your a little on the lean side. I am running 390's at 9000 and up.
oh. well that might be my problem. any ideas on how i should go?
I'm gonna say at least 400's. maybe up one more for the head. I would ask your local dealer. Probably save you some time. 
yea i got some 420s laying around but that seems pretty big. does the pipe, can and head set up lean it out a lot? and also i am curently porting and polishing my cylinders. what will that do?
A
Arctic Thunder
Well-known member
The pipe and can will make a difference. Not apple to apples here but on my 900 AC Stock I ran a 350's. With the pipes and can I had to run 390-400 and it was still on the edge. So I ran 400-410's. So it can make a big difference.
Also I don't believe you need to add any fuel for the head. You just need to run good fuel with a high enough octane to prevent detonation.
Thunder
oh i might try the 420s see what they do
I thought that the new plug was just because the ground was breaking off. How does it make it run lean.
Thanks for the info.
Mutt
whos head and what compression are you running, is that standard bore, im running an 830 withh 440 mains,i was running 13.5/1 domes and kept having major detonation problems on premium pump gas, switched to 12.5/1 domes and is running like a top now. didnt have to change clutching at all with dome change cause sled is running that much better.
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