I bought a 2004 blaster that runs but will only idle it will not accelerate at all just bogs out found low compression upon inspection found brand new piston is marked 66.42 mm bore size is 66.60mm is this where my low compression is coming from
bore size for piston
- Thread starter rhyno2565
- Start date
Before you tear into it. The parking break can make the 03-06 Blaster only idle. The TORS can also affect the quad in the same way. If there is any doubt about the compression being low I would look into removing the TORS and parking break.
TORS will not lower your compression. Yes, when parking brake is engaged with the TORS still installed, it will bog the engine. BUT it will not affect compression at all. If the compression is low, he needs a top end rebuild.
Remember to always check the piston size, clearance and bore size after getting everything back from the shop. "Measure Twice, cut once" Same principle. Good Luck!
Thanks @darealblaster ........ what I said was "If there is any doubt about the compression being low I would look into removing the TORS and parking break."
I never said the TORS would affect the compression, the tors will keep your quad from coming off idle.
I never said the TORS would affect the compression, the tors will keep your quad from coming off idle.
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.
Has it been heat cycled and re tensioned.
Did you do a leak test on the engine before you started it?
Did you do a leak test on the engine before you started it?
To condition the copper head gasket and to start the ring bed in one should bring up the engine to operating temp and let cool for 30 mins.
Do three cycles then after the 3rd has cooled, re tension the head and cylinder nuts as the expansion and contraction can cause them to leak.
It is recommended that the engine be pressure tested at the carb boot to ensure it is air tight.
Any air getting in can cause bogging, over heating and a cooked piston!
Has the carb you swapped been jetted to suit the engine mods?
Do three cycles then after the 3rd has cooled, re tension the head and cylinder nuts as the expansion and contraction can cause them to leak.
It is recommended that the engine be pressure tested at the carb boot to ensure it is air tight.
Any air getting in can cause bogging, over heating and a cooked piston!
Has the carb you swapped been jetted to suit the engine mods?
So I know it's been awhile but I have finally got everything up and running and here is what I found. The piston was the incorrect size had to have the cylinder bored. Still wasn't running right it turns out that whoever bypassed the tors system had no idea what they were doing and that a jumper wire in the connector that wasn't making contact. Fixed that and now it runs great
That's great. Thanks for reporting back. Hopefully you still followed blasters advice on the heat cycles and leak test. Also normally there is a break in period of 2 tanks of gas at no more than 3/4 throttle. Then you need to make sure the jetting is correct. And then ride it like you stole it
I'm a few drops away from finishing the second tank but now that yo mention the jetting I must ask some advice on that I have installed a dg full exhaust I have a reed spacer no air box lid with a k&n filter and Boysen reeds. I have a dyno jet kit but I don't know what jets to use with the upgrades I have
At sea level, this may help.
DG= #260 main jet.
Aftermarket air cleaner + 1 or 2 size larger.
Air box lid off +2
32:1 pre mix +1
Cold weather + 1 or 2
Needle in the middle slot.
32.5 pilot jet
Plug chop to confirm, as temperature, elevation and humidity come into the equasion
DG= #260 main jet.
Aftermarket air cleaner + 1 or 2 size larger.
Air box lid off +2
32:1 pre mix +1
Cold weather + 1 or 2
Needle in the middle slot.
32.5 pilot jet
Plug chop to confirm, as temperature, elevation and humidity come into the equasion
