Planet Minis

JustinW · 07-08-2008, 01:31 PM

Hello,

I have a XR100 in a YSR50 chassis that I use for road-racing on a local kart track. At the last race, we noticed that the bike smokes quite a bit when I'm off-throttle, but nothing noticeable under power. The bike seems to have the same power that it's always had. As far as setup, the motor is a stock 2000 with a FMF pipe, UNI clamp-on foam filter, 38 or 35 pilot, 102 main and the needle is at the 2nd notch from the bottom(1 lower than stock). Also, I'm in central Ohio.

I'm assuming something needs replaced, but what: rings, valve seals,....
I hope someone has experienced this before and can show me the right direction to go.

Forgive me if this has been covered before. I searched some and didn't find anything that I thought matched this.

SUZUKIRM12594 · 07-08-2008, 01:33 PM

Yup....Sounds to me like you're going to need new rings.

BlackBeard · 07-08-2008, 01:50 PM

i dont understand who would tear apart their engine and only replac e rings? if i were you id order a new piston rings and valve seals. install and lap your valves before re-assembly.

SUZUKIRM12594 · 07-08-2008, 01:52 PM

Quote:

Originally Posted by zbbt

i dont understand who would tear apart their engine and only replac e rings? if i were you id order a new piston rings and valve seals. install and lap your valves before re-assembly.

Agree. Cus its just a matter of time before your're gonna need to replace the rest. So what better time to do it than while your engine is open?

BlackBeard · 07-08-2008, 01:53 PM

Quote:

Originally Posted by SUZUKIRM12594

Agree. Cus its just a matter of time before your're gonna need to replace the rest. So what better time to do it than while your engine is open?

X2

firepower354 · 07-08-2008, 08:25 PM

Stick an intake guide seal on it and pound it for the rest of the season. Just do the rope down the plug hole trick to swap it. Have the parts around for a real rebuild later.

JustinW · 07-09-2008, 01:32 PM

Quote:

Originally Posted by firepower354

Stick an intake guide seal on it and pound it for the rest of the season. Just do the rope down the plug hole trick to swap it. Have the parts around for a real rebuild later.

I went ahead and ordered some parts from BikeBandit.com. but they only showed a valve stem seal on the exhaust valve, is there supposed to be one on each valve? Also, I don't see 'intake guide seal' on the parts list, do you know the BikeBandit.com part number? This is the first time I've really done anything more involved than just changing the oil on this motor, although I did get a service manual with this order.

Just out of curiosity, what is the 'rope down the plug hole' trick??

bat999 · 07-09-2008, 03:16 PM

Quote:

Originally Posted by firepower354

Stick an intake guide seal on it and pound it for the rest of the season. Just do the rope down the plug hole trick to swap it. Have the parts around for a real rebuild later.

+1, but I was thinking the exhaust valve was the one needing the seal...because its only smoking under decel.....????

slow600 · 07-09-2008, 03:28 PM

i believe older 100's only had one valve seal and the newer ones had two.

firepower354 · 07-09-2008, 07:12 PM

Yup, they added an intake seal. Follow their lead

High intake vacuum on decel is often the intake guide/seal.

Soft rope (not all of it) down the plug hole, with the piston bumped up against it on the compression stroke will give the valve something to keep it from falling in while you compress the spring and pull the keepers. A home made tool will help if you're up to it. Then you don't have to pull the head. Learned the trick from a dragrace buddy who didn't want to trash $100 each head gaskets swapping $400 valve springs every couple races. Compressed air will work, IF it's well sealed.

07-08-2008, 01:31 PM	#1 (permalink)
JustinW PM Newbie Join Date: Jul 2008 Posts: 2	XR100 smoking off-throttle Hello, I have a XR100 in a YSR50 chassis that I use for road-racing on a local kart track. At the last race, we noticed that the bike smokes quite a bit when I'm off-throttle, but nothing noticeable under power. The bike seems to have the same power that it's always had. As far as setup, the motor is a stock 2000 with a FMF pipe, UNI clamp-on foam filter, 38 or 35 pilot, 102 main and the needle is at the 2nd notch from the bottom(1 lower than stock). Also, I'm in central Ohio. I'm assuming something needs replaced, but what: rings, valve seals,.... I hope someone has experienced this before and can show me the right direction to go. Forgive me if this has been covered before. I searched some and didn't find anything that I thought matched this.

07-08-2008, 01:33 PM	#2 (permalink)
SUZUKIRM12594 3rd Gear Member Join Date: Jun 2008 Location: Glendale California Posts: 2,449	Re: XR100 smoking off-throttle Yup....Sounds to me like you're going to need new rings.

07-08-2008, 01:50 PM	#3 (permalink)
BlackBeard "ZBBT" Join Date: Oct 2007 Location: 50 riders Posts: 1,772	Re: XR100 smoking off-throttle i dont understand who would tear apart their engine and only replac e rings? if i were you id order a new piston rings and valve seals. install and lap your valves before re-assembly.

07-08-2008, 08:25 PM	#6 (permalink)
firepower354 3rd Gear Member Join Date: Oct 2006 Location: Flint MI Posts: 6,223	Re: XR100 smoking off-throttle Stick an intake guide seal on it and pound it for the rest of the season. Just do the rope down the plug hole trick to swap it. Have the parts around for a real rebuild later.

07-09-2008, 03:28 PM	#9 (permalink)
slow600 2nd Gear Member Join Date: Feb 2007 Posts: 368	Re: XR100 smoking off-throttle i believe older 100's only had one valve seal and the newer ones had two.

07-09-2008, 07:12 PM	#10 (permalink)
firepower354 3rd Gear Member Join Date: Oct 2006 Location: Flint MI Posts: 6,223	Re: XR100 smoking off-throttle Yup, they added an intake seal. Follow their lead High intake vacuum on decel is often the intake guide/seal. Soft rope (not all of it) down the plug hole, with the piston bumped up against it on the compression stroke will give the valve something to keep it from falling in while you compress the spring and pull the keepers. A home made tool will help if you're up to it. Then you don't have to pull the head. Learned the trick from a dragrace buddy who didn't want to trash $100 each head gaskets swapping $400 valve springs every couple races. Compressed air will work, IF it's well sealed.

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