Bogging at 50 mph By seanstr (Read 1,044 times)

[seanstr]

So I'm very close to getting everything, high mpg and high top end.

I am currently bogging at 50mph. If I lean the needle clip it bogs at lower mph. Problem. I am the richest setting for the clip. I'm on a 105 main jet. When I go to the 106 and leanest setting on clip it runs terrible. I have tried placing a small washer in there too richen up the setting for the needle but it's not enough.

Any ideas where to go from here?

Do one change and check results.

[czmdiver]

Bro I have been folowing along your saga
I rally think either something else is wrong or ya got the carb all jacked up.
Ive done quite a bit of jetting on both my 24mm and 26mm CVK carbs. I've made some drastic changes and the scoot still went down the road.
Making One Main Jet size change you should Not have to make such a drastic change with your Needle Jet clip position. you Most likely shouldn't have to change it at all. your going from one extreme clip position to the other.
The Needle only effects just above 1/4 throttle to just over 3/4ths throttle, at WOT your on the Main jet.
See Graph below.
Hope this helps, good luck

[cyborg]

Could be needle taper,,,I had a hell of a time with my Vespa et4 150cc ,,I was running a mikuni VM round slide on it and had a mid throttle "stumble",,I went thru mikunis application tables ,,found out the one that was in the carb ,,ordered one of each on either side of the taper I had ,,,first replacement in cured the problem,,this is one of the reasons I run mikuni,,,no other company gives their research freely like them,,,

[seanstr]

Contacted the mechanic I trust. He said the belt has to be the correct belt or it will act up and not allow the scooter to function correctly. He is checking on the belt size from Lance, however he tried this 3 months ago and they said they have 3 engines for this model and year. So if I am lucky I can get them to get the correct belt.Then I will adjust the main jet.

Do one change and check results.

[seanstr]

I found out that my compression had changed. Used to be at 210 which is high. Now it's at 90. So I took off the valve cover and checked the valve clearance at Top Dead Center. Still set correctly .004. So I must have a piston ring issue? There's no smoke so I'm confused.

[trashtruck12172]

put a small amt of oil (like a tspn) in the spark plug hole and retest compression. if compression increases, it may be a piston issue. if no change in compression it may be a valve issue or bad head gasket.

[cyborg]

He did the test wrong

[seanstr]

I did it completely wrong, no throttle on WOT. Oops!

Do one change and check results.

[seanstr]

I achieved 55mph. Yeah me

Do one change and check results.

[cyborg]

Nice!

[seanstr]

Jun 14, 2017 20:29:10 GMT -6 cyborg said:

Nice!

Only took 9 months and nice hot weather. Lol

[cyborg]

Lol,,, yes it's been long and painful,,, many would have thrown in the towel quite a while ago but you stuck with it and sorted out,,, there's a piston right there

[seanstr]

Also, fun thing happened, I am getting 94 mpg now. last fill up, I had to check the results twice. Did I fill it up the same as before, was the math correct, etc.

Do one change and check results.