I just purchased an 04 blaster from someone that performed a top end rebuild and gave up because once they got it together as soon as you hit the throttle it just cuts off. So far I cleaned the carb, replaced the reads, and performed a compression test. I found that it only had 60 psi. So I pulled the head and the jug and found that the piston and rings are in great shape the cylinder walls look good. Any ideas I will try anything to fix this thanks
wont accelerate just bogs out
- Thread starter rhyno2565
- Start date
People have said that about the park brake but there isn't one on the bike. I was wondering would an exhaust leak cause this
check to see that the piston is not in backwards and nothing is cracked or hairline fractures in cylinder,cylinder head,check for fuel flow from tank to carb....this is the wire that we are talking about on the parking break...is it the stock cluth lever and perch as pictured? if so unplug it at both ends and then try to rev it. one end is under nose/headlight
60 psi ?? what kind of compression tester do you have? did you hod throttle wide open and kicked till it stopped rising in psi? i would say 3-5 times of kicking. i would measure what size piston and bore you have other person might have put wrong size in but im not sure if it would start at all with only 60 psi
Last edited:
It's already Un plugged it was removed and has a new clutch lever they also deleted the oil injection and the tors how do I know if the piston is in backwards?
Well it wouldn't start anymore after I put the carb back on. The first time I did the test I didn't hold throttle open got around 55 with wide open I got 60 compression tester is a snapon
your compression should be at least 120 psi with a fresh top end,although the cylinder head has a lot to do with the compression as well.if your gauge is indeed correct then you definetly do not have enough compression,there should be a arrrow pointing towards the exhaust side of piston and two ports at the carb side.
HERE IS INSTRUCTIONAL VIDEOS COURTESY OF KEN OCONNOR RACING
http://www.blasterforum.com/threads/kor-engine-assembly-vids-no-crank-puller-needed.51169/
HERE IS INSTRUCTIONAL VIDEOS COURTESY OF KEN OCONNOR RACING
http://www.blasterforum.com/threads/kor-engine-assembly-vids-no-crank-puller-needed.51169/
The gauge has been accurate for me on cars I'm gonna check the piston in the morning hopefully it's backwards that would be great but we'll see in the am if it's backward am I going to have to replace anything when I turn it around
if it is scored or damaged yes,and your not supposed to use circlips, and gaskets again.If you can post pics on here take so pics it might help identify your problem or problems
If the piston is in backwards and you have been running the engine for a while there is a fair chance that a ring has snagged a port and done a little damage.
On the bright side if the machinist has put a decent chamfer on the ports, little or no damage will have been done.
I would bet you eggs are eggs that no heat cycling was done to bed in the rings since rebuild.
After a while of operation the head and cylinder need to be re tensioned to allow for gasket conditioning.
If you take the reeds out you should be able to see two windows in the piston if it is in correctly. That will save you the cost of a new head gasket.
On the bright side if the machinist has put a decent chamfer on the ports, little or no damage will have been done.
I would bet you eggs are eggs that no heat cycling was done to bed in the rings since rebuild.
After a while of operation the head and cylinder need to be re tensioned to allow for gasket conditioning.
If you take the reeds out you should be able to see two windows in the piston if it is in correctly. That will save you the cost of a new head gasket.
Last edited:
Recheck the tors removal. It is done differently on a 2004.
http://www.blasterforum.com/threads/2003-2006-tors-delete-proper-wiring-heres-what-i-did.48477/
It is hard to believe it would start with 60 pounds of compression. I would double check this before tearing into it.
http://www.blasterforum.com/threads/2003-2006-tors-delete-proper-wiring-heres-what-i-did.48477/
It is hard to believe it would start with 60 pounds of compression. I would double check this before tearing into it.
So I went out and looked and the arrow on the piston is facing forward and the size is 66.42mm which is twenty over I'm headed to work to get tools to measure bore size. It seems the piston is too small it's got a pretty good amount of play side to side
Ok so it's been awhile but it turned out the piston was a .020 over piston in a head that was just a hair shy of .030 over but the bore was also not straight probably due to running with wrong sized piston. I had the head bored to .040 over installed a new piston. It runs much quieter at idle BUT when I try to give it any throttle it bogs out. Any ideas?
And just for a little background info I have tried swapping carbs made no difference it has new reeds it has a new gasket set and of course piston and rings.
And just for a little background info I have tried swapping carbs made no difference it has new reeds it has a new gasket set and of course piston and rings.
Similar threads
