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leftywoody

leftywoody

Member
Aug 23, 2008
405
0
16
Lagrange Indiana
I have a bone stock 66/80 cc bees nest on my 26inch mountain bike .Usually I ride at a moderate speed or less just to be nice to the engine . Today I rode a few miles and deciced to pour the coals on and see how fast I could go .At top speed the rpms started to waver slightly up then slightly down then up then down . So I backed off and went to a moderate speed and it ran fine . The screen was clean in the tank, the gasline had no bubbles or air pockets and it never missed a beat while running .I do run my mix a little rich and the plug looked reasonably clean . Could this be a float issue or something else ? One other problem seems to be haunting me lately .Only after the engine gets warmed up ,when I come to a stop and pull the clutch in , it revs up too much. I correct this by turning the screw slightly out .Then the next time I ride the engine is cold and won't idle until I turn that screw slightly back in . I will test for a gasket leak unless you guys think it is related to something else . I have only maybe 50miles on this engine if that and it has run without issue until recently . thanks for any advise John
 
Ghost0

Ghost0

New Member
Mar 7, 2008
763
1
0
Bellingham, WA
High idle after an engine is hot is very symptomatic of an air leak causing a lean condition. Check your intake manifold gasket and carb to intake manifold connection for an air leak.
 
leftywoody

leftywoody

Member
Aug 23, 2008
405
0
16
Lagrange Indiana
Ghosto, I had to pull the engine out to drill out and replace a broken stud in the mount . While it was out I took the intake off and was examining the type of sealer that was used. It looked like a combination of dry wallpaper paste and Scotch tape . For only 50 miles wear and tear it was not impressive . I cleaned and resealed it with some quality RTV sealer and it seems to be running fine. This repair should be done with any and all engines before they are installed fresh out of the box . thanks ....John
 
2door

2door

Moderator
Staff member
Sep 15, 2008
16,302
175
63
Littleton, Colorado
Ghosto, Thanks for a good response.
John,
The kit supplied intake and exhaust manifold gaskets are notoriously fragile. I use them for templates only and make my own from good quality gasket material. In addition to the intake gasket I use 'Permatex Black' silicone gasket sealer. Also coat the manifold and the throat of the carb being sure to fill the slots before installing the carb. You don't want too much sealer, just enough to coat the surfaces. I'm a bit anal about things so I rough up the surface of the intake where the carb slides on, especially the chrome plated steel ones. This gives the sealer more 'bite'. These things should assure you won't have any air leaks on the intake side. As for the exhaust I don't use a sealer just a 1/8" thick gasket torqued just enough to flatten the lock washers then a gentle twist more. Metallic gaskets are available and they work well if there is a good flat mating surface on both the exhaust pipe and the cylinder. Any irregularities here will require a lot of torque to get a good seal and that's asking for trouble. You can true up the mating area of the exhaust flange with a flat surface and some course sand paper. The cylinder is usually fairly flat but check it with a straight edge before assembly.
Tom
 
leftywoody

leftywoody

Member
Aug 23, 2008
405
0
16
Lagrange Indiana
thanks for all the good advice . I don't think there was any gasket at all between the intake manifold and the cylinder head. Just some dried chinese toothpaste . Do some kits come with a paper gasket at that connection ? I guess they figure it will be good enough to last through the first tank of gas .
 
S

Sparks66

New Member
Nov 4, 2009
44
0
0
San Jose, Ca
I had the same idle problem. High revs at idle or the engine dying when it's supposed to idle. This symptom just showed up out of nowhere and I thought it had something to do with the new exhaust I put on. I tried cleaning the carb, messing with the throttle, re-torquing the head, messing with the idle, sealing the carb to manifold with silicone and messing with the throttle again all to no avail. Disgusted, I decided to put a new gasket on the exhaust. While I was at it, I decided to install a new gasket on the manifold to block and that's when I discovered that the top part of the orginal gasket was nowhere to be found. Happily, I made a new one and am looking forward to see if that fixes it as soon as the silicone dries.
Sparks
 
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Nerevar

New Member
Oct 9, 2008
27
0
0
Pennsylvania, USA
While on the topic of silicon sealants, put a bead on the seam of the magneto gasket cover. I had a magneto and CDI get fried from going through a little puddle. :(
 
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