Dissapointed and in a dilema....

[phats]

So ive been classic racing for some years, mostly on a 360 MX yam and a TT500 yam. I restored and rebuilt a 79 GS250 KTM/Penton earlier this year and have rode in three races so far and all i can say is that im a bit dissapointed in some respects....

The bike itself handles great, footrests are a little far forward for my liking, but other than that, no complaints. Now the motor, 90% of the riding i do is tight, muddy woods with lots of gradient changes, the motor just seems to bog down really easy under load, i find myself constantly having to clutch it and drop down as low as 1st. Once you get in the power band, its a joy to ride, fast as stink, but there just seems to be hardly any bottom end torque what so ever??

- Running totally standard jetting & ignition settings.

Is this just the way they are??

Im now toying with the idea of grafting an 83 reed valve barrel on, or even dropping a 400 lump in.

Any ideas??

[Larry Perkins]

My guess is your Bing carb needs some or all of these-Slide, needle, and needle jet.  That motor has a lot of down low for a piston port motor.  I assume your gearing is good for condition.

[Mick Milakovic]

Like Larry says don't forget gearing.  My bike acted like it was bogging with no power in the tight stuff until I started running a 12/52 sprocket set on my 250 HS.  Now it never feels like bogging on me, it still feels too fast for the tight stuff.  I'm going to a 12/54 ASAP.

Mick

[tomale]

What Mick and Larry said is true.. your bike needs to be geared to fit your situation.. when they built that bike they set it up for what was is normal or usual.. On my 250, the bing got to the point were it really did not work like it should. My solution was to replace it with a Mikuni, I was shocked how much of a difference it made.  I had change the gearing before I changed the carb to get the motor to pull better in tight situation and after I installed the Mikuni, I ended up switching the gearing back because I was shifting too often. Everyone thought that I was riding a 400 but it was just a 250.. I could easliy stay with my buddy's on 400's A better solution than a Mikuni would be to put a flat slide carb on it like the Lectron. They are nice because if you ride the bike at any altitude adjusting the carb is super easy.. do a seach to read what others have done with the lectron that they have put on their KTM.

Thom Green,Still crazy after all these years!
76' 250 MC5 (orginal owner)
74' 1/2 440 maico
70' 400 maico (project)
72' cr125 Husky (project)
93' RMx 250 suzuki

[phats]

Well im running 13/52, the gearing seems alright in the woods, its slow enough in 1st and i regually get it into 6th up the tracks...

Im quite happy to put a mikuni or lectron on, i know there is a bit of work involved....

Just out of curiosity, what are the 400 motors like in comparison, when considering torque and bottom end performance?

Chris

[G Ellis]

Run a gear 13/56, you will need to be in the upper gears. Has your motor been rebuilt? Match the cases to the cylinder will gain 3to5 more horse power.Give me a call I can help you. 217 260 0237 Later Gary

[454MRW]

Assuming that you replaced the crank seals when you did the rebuild, what did you set the ignition timing at? The timing should be right around 2.2mm before Top dead Center. My 79 MX-6 250 had tons of bottom end torque and would pull hard from just off idle. Mike

Michael R. Winter
I enjoy rebuilding and appreciating Pentons!
1974 250 HS Pentons-1980 KTM 175-400'S
1975 Can Am 175 TNT & 77 250 Black Widow
1979 Husqvarna OR390
1976-78 RM & 77-79 PE Suzuki's
1974 CR250M 07 CR125R 79 CR250R