jetting help

[Dale Sonnenschein]

I'm trying to get my 73 jackpiner running good for VMD. The problem is when I lug it down it loads up. It has a fresh bore, paper air filter, B9HS plug, 150 main. 30 pilot, I can't read the needle numbers but I have tried all  4 positions. The float level seems good I have adjusted the air screw.  Fresh ethanol free gas at 35:1. I have tried a 35 pilot. The plug is a dark grayish color. The bike runs very good other than low rpm loading up. If I catch it early I can pull in the clutch and clear it out and keep going. Any idea's on what I am missing?

Thanks

73 Jackpiner
73 Husky 360 WR/RT
76 Husky WR360
78 husky cr250
10 ktm 250xc
02 bmw r1150r

[G Ellis]

A 9HS is too cold for that motor. You need to run an 8HS. This will make it run better.

[brian kirby]

Are the needle jet and needle new?

Brian

[DKWRACER]

Wallowed needle jet?
Tom Brosius

[gooddirt]

paper air filter ? weak motoplat

[454MRW]

Fresh bore? Is this the first time out since rebuilt? It wouldn't be the first time a rag or paper towel wad that was forgotten and left in the exhaust port intended to keep debris out found its way into the exhaust pipe. Also mice tend to build nests in there over the winter months, darn critters. Mike

Michael R. Winter
I enjoy rebuilding and appreciating Pentons!
1974 250 HS Pentons-1978 KTM 250'S
1975 Can Am 175 TNT 250 conversion
1976-78 125-400 RM's & 79 PE250 Suzuki & 2012 DR650
2007 CR125R Honda
1977 MC250 Maico

[fastwillie8568]

My 73 and 74 Jackpiner is 150main 30 pilot 1/1/2 air screw 40:1 spectro and a # 1 needle and a 273  they both run great and my float level is a little low

[Dale Sonnenschein]

I'll try an 8 tomorrow.
 
Brian and Tom,  Both are original. but I did get a 273 needle jet with the bike. I haven't checked the one in the carb. But I am guessing it's the stock 276. I can't tell the numbers on the 2 needles I have.

Mike, I only rode it briefly before the bore but it did it then too.

Gooddirt, I was going to pick up a filter at VMD and see what it does.

Maybe I'll pull the carb tomorrow and see what needle jet it has, and try the 273.
Thanks for the help, I'll post my progress.

73 Jackpiner
73 Husky 360 WR/RT
76 Husky WR360
78 husky cr250
10 ktm 250xc
02 bmw r1150r

[Dale Sonnenschein]

Ok, I  got a little ambition tonight. I pulled the carb and it had a 276 needle jet. I put the 273 in with the skinnier needle ( it was in the bike when I got it) 2nd groove. I don't see a number on either needle but one looks fatter. I'll do a test ride tomorrow. Hopefully this will help. I'll get a B8HS tomorrow too.
Thanks again for the help

73 Jackpiner
73 Husky 360 WR/RT
76 Husky WR360
78 husky cr250
10 ktm 250xc
02 bmw r1150r

[brian kirby]

If the needle jet and needle are not new then you found the problem.

Brian

[Dale Sonnenschein]

SO I put a new plug, B8HS in and the 273 needle jet and it ran pretty good. In the end I wound up being just what it shows in the manual except the 273 jet. Now the bike runs real good and it hasn't loaded up on my last test ride. Thanks for the help. See you all at VMD

73 Jackpiner
73 Husky 360 WR/RT
76 Husky WR360
78 husky cr250
82 husky wr430
10 ktm 250xc
02 bmw r1150r