Help having problems with a kit

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furnaceman
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Help having problems with a kit

Post by furnaceman »

Ok guys and gals I just installed my polini 177 kit and now it runs great but sometimes it wont shut off and revs right up high the kit's instructions said to leave the jet in but it seems to be dieseling as kevin thought I noticed when i removed the old jug and piston that the rings had failed a bit and there was some blow by also the head to jug was leaking so i think that my concerns of little power before were just losing compression in the cylinder .
However I still would like some feedback as to what may be wrong.

thanks Bruce.
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jbcollier
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Post by jbcollier »

You have an air leak somewhere. So a bad seal (less likely as it was OK before but seals can die sitting over the winter), or a leak from the kit's installation.

Pull it back down and double check that the cylinder base gasket didn't get torn -- use some permatex aviation gasket goo while you are in there. Make sure the head is tightened properly -- do it evenly in three stages and using a criss-cross pattern.
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Angelo
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Post by Angelo »

Bruce...didn't I tell you John would know? :D
�Long live vintage motorcycles that are too tough to die...�

- Dustin Kott-
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Dennis
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Post by Dennis »

It could also be due to far too lean of jetting? Did you 'up' the jetting at all after you installed the kit?
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furnaceman
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Post by furnaceman »

dennis no i did not up jet yet as the bike was running really rich before

now i have it running good the plug isn't showing a lean mix but the only thing is it dosn't come down to idle when driving between gear changes.
takes a long time to drop down .
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jbcollier
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Post by jbcollier »

Pull the choke on. Does it behave better? Then Dennis is right.
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furnaceman
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Post by furnaceman »

Im gonna try the 108 jet i got from dennis when i got the sito pipe and see what happens.

Bruce
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furnaceman
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Post by furnaceman »

OK here's the update I pulled the engine off again and sealed the gasket to case like john said when i removed the jug and head the piston and bore were very saturated with gas (is this supposed to be like this?)double checked and couldn't find any obvious air leaks. installed the 108 jet i have instead of the 98 stock one. ran ok but after it warmed up if you blip the throttle it takes off like before and revs out of control so i guess im not going to be riding much this year unless it is fixed it's almost too unpredictable to go anywhere i don't want to be out on it and have it take off on me that could be fatal.

Bruce.
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jbcollier
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Post by jbcollier »

Does it settle down if you pull the choke out? I am away right now but I am sure we can sort it out.
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Angelo
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Post by Angelo »

Bruce,
The riding season hasn't even started yet! I understand....I have been frustrated with situations like this in the past, but now there are many of us, and like John says, we will sorted it out!

Cheers
Angelo
�Long live vintage motorcycles that are too tough to die...�

- Dustin Kott-
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furnaceman
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Post by furnaceman »

It dosen't change when I pull out the choke I guess I just need to be more patient

Bruce.
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jbcollier
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Post by jbcollier »

It should stall when you pull the choke out when it is warm. It shouldn't be too bad to sort out. We can discuss at Sunday's meeting.
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Dennis
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Post by Dennis »

***Warning...long drawn out boring answer/opinion ahead***

Yes, pulling the choke should stall it if everying is right. The choke is not a 'choke' in the traditional sense of the word. It doesn't choke the venturi of the carb like a butterfly valve. It's actualy an enrichener. It floods the system for cold starts.

If you can't find signs of air leaks arount the cylinder then I suspect (and agree with John) the crank seals...one or both of them are shot. These seals need to be in good shape to provide sufficient primary compression (when the fuel is compressed around the crankshaft below the piston). If the primary compression is too low there is not enough pressure to deliver the fuel charge to the to the top of the piston through the transfers once the piston clears the ports.

Continuously trying to start it, choke or no choke, rejetting or whatever will not work. You will always 'think' it's running too rich.

You mentioned after a tear down that the piston and cylinder were satuarated with fuel and oil. An indiction that primary compresion is low. Did your exhaust have gas in it too? Drain your gearbox oil. Is there the smell of gas? If so your clutch side crank seal is toast. Complete engine teardown needed. But don't rely on this theory. I've had had several scooters that had a bad clutch side seal with no gas in the gearbox. You can on some models change the flywheel side seal without a full teardown. But test it first. Remove the flywheel and stator. Have someone kick the pedal over and over while you spray windex on the seal around the crank. Get down close and watch if any bubbles larger than that of normal windex form. Do this with a warm engine so the seal is soft. To change it you can (on some models) pull it out with a seal pick. Grease a new one and press it in making sure the inner sealing lip is not flared out toward you.

You can't measure primary compression easily. you need what is known as a leak-down tester. Don't mistaken primary compression for the compression above the piston. That is the secondary compression and easily tested with a gauge that threads into the spark plug hole. Having sufficient secondary means nothing other than you have a good seal between the head and barrel and a good set of piston rings.

If it is none of the above I would look at the quality of your ignition componant.

It's not an exact science...it's called troubleshooting.

I hope this helps.

Dennis
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furnaceman
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Post by furnaceman »

Thanks for the input dennis i wonder if the seals are bad the bike only has 2500 kns on it and it wasn't acting funny before the jug and piston change. I wonder if mabye it's a bad float in the carb I really didn't run it much after the trip to vegas. mabye all the bouncing on the trailer has something to do with the float or needle.

Bruce.
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Dennis
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Post by Dennis »

Maybe all the bouncing on the trailer loosened one of the ignition componants or wires?
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