air leak?

G

guigui

New member
Joined
Apr 3, 2015
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46
Location
Quebec Canada
I have a phazer 2 with what looks like a AAEN pipe, I swapped exciter carbs (dual VM38's) and have been chasing a lean condition on one cylinder since I got it. Hence the exciter carbs. on PTO side it runs quite poor as far as I can see, idling is pretty good but any extended running leads to the electrode getting quite greyish. not exactly white but far from the chocolate brown. I swapped the spark plugs, swapped plug wires, swapped carbs and the lean condition did not move. I thought about a crank seal, tore down entire engine, changed both crank seals, base gaskets and head gaskets. Compression is about 110 and even on both sides. I sprayed carb cleaner around the intake to no avail. I'm a bit lost here, the only thing I can still think of would be a miniature crack somewhere in the engine that draw air only when the engine is running at quarter throttle and up but quite a hard guess. For now I raised the needle to the Highest on that side to try to keep alive for what remains of the season.

Also when I tore it down I did not find any obvious sign of oil leaking from the engine
 
if you just put the ex carbs on the sled .....the carb jetting specs are no where close to what you need and could just be your jetting ..... aside from running 38 flats on these sleds for years i have also dialed in 38mm rounds from stock to full mod trim .....here is what you should have for jetting with a aaen pipe and stock motor with either completely gutted air box or filters
2.5 slide
6dh3 needle 3 clip position
40 pilot
Q-8 tube
340 main
air screw at 1 turn this is for 1200 ft elevation and 25* temps good down to 0* .....with modded engine and good reeds mains may need to go as high as 420 and bump pilots to 42.5
 
I'm a bit embarassed to say I found my leak. There were no clamps on the crosstube between the 2 boots. It was that way when I got it so I didn't thought much about it. pitung clamps solved a bit of the issue but you are right to say they are too lean from the factory, I had to raise the needles to the maximum to get it to run OK, not real good but OK.

I find it surprizing that carbs that were on a 570 are too lean for a 480, those little fanners are really thirsty for gas.

Anyway I will finish the season that way end before next winter, I will try your jetting, you seem quite knowledgable about those sleds
 
quick lesson on jetting .............motor size has nothing to do with jetting requirements .............air speeds at given throttle position and motor needs decide jetting yes i can go further into detail ..............but look at it this was a 570 has more suction/air speed than a phazer to start that is the main reason for need for richer jets one of my personal mod phazers with 38 rounds runs 450 mains ........not that it has not air speed but flow is that much better
 
Sure if you gut the airbox, there is less restriction before the carb, therefore less vacuum in the carbs to pull the fuel and also more flow, witch requires more gas
 
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