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Old 02-02-2013, 02:34 PM   #14
cheap bastard
Joined: Oct 2010
Oddometer: 32
The 125 riva (in my experience) starts very poorly in sub 50 degree weather if it's allowed to sit for a couple days. My personal investigation has shown, at least on my scooter, with an in tact clean carb, the float bowl nearly dry by day three. There is very little vacuum at cranking speed and it is pulsing, of course. The vacuum petcock has little chance to supply enough fuel to the empty chamber, so cranking times are very long. My engine showed 160 psi during a compression test. Cranking vacuum peaked at 7 inches. Clear fuel filter installed, Fuel shows low flow when cranking. If a vacuum is applied to the petcock before trying to start the engine cold and dry, filling the float chamber, starting is easy.
Conversations with a couple guys that have used these machines for years has taught me that cold start issues are very common, at the least.
The Grizzly 125 ATV may have a related engine with a proper choke, but I came up with no supporting info. Changing to a different model's carb was more work than I wanted to expend on this bike, so I looked for other solutions. A "T" in the vacuum line, with a syringe and hose could provide a vacuum source for the petcock. A check valve in the carb side of that arrangement would be needed, but a way to defeat it would also be required to shut the petcock off as it would hold a vacuum after shut down. The other idea, the one chosen, was to port a hose long enough to route to a handy position. The hose was fastened over a nipple inserted in the air box. Starting fluid can then be sprayed into the air box without dripping it all over ones hands. There is a cap on the hose to avert having unfiltered air drawn into the engine.
One could also just start the machine every day or two and put a battery charger on it occasionally for maintenance.

cheap bastard screwed with this post 02-02-2013 at 02:36 PM Reason: grammar
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