'Piner Pep-ups?

[Frenfroe]

I've seen the posts on the 250 modifications, especially the Carl Cranke mods. What are options for the 'Piner? I use it mostly trail riding and plan to ride a few enduros and the ISDTRR. It won't ever be MX'ed. Mine seems a little flat down low but really hauls up high, but I mostly ride trials and maybe I'm just used to a LOT more torque at low rpms.

Mine has a late '75 motor. It's been geared down slightly and I have a set of Boysen reeds for it (not installed yet) and a new aircleaner, everything else is stock, including the jetting.

Thanks, Frank

 

[Larry Perkins]

Make sure your timing is spot on for one thing.  

Another thing is it did not come with a reed so it may not be jetted right.  Also worn reeds could be the culprit so you might try putting the new ones in.  

The other thing I see on alot of Bings with that symptom is a worn needle jet.  Has the needle jet been replaced recently?  Bing carbs over time ovalize the needle jet and become larger so that they are rich just coming on the throtle(as you roll it on there is a slight bog).  

Also make sure the slide is not worn.  If it is getting a smiley face on the slide it is too worn and the same thing will occur.  

If you are changing the needle jet go down one size from stock and it should crisp up too.  These are all possibilities that I see real often.

I think the Jackpiner is a little pipey anyway and always preferred the 250 powerband better.  But you know what they say different strokes for different folks.  Or should it have been different bores for different folks?  Good luck.

 

[Frenfroe]

Larry, it didn't originally have a reed? I'll double-check the motor date, but I think it was July 75. The frame is marked 54 511xxxxx. When did the KTM 175 switch to a reeded motor and would a reeded topend drop-in? Everything sure looks stock (airbox, boot, etc). I just thought a reeded 175 should have a little more bottom end. It seems to run clean already.

 

[Larry Perkins]

Reed would help bottom end but KTM to the best of my knowledge did not do this till the 80's.  I could be wrong but I don't think so.  No Pentons were reeded for sure.  Not stock at least.

 

[Frenfroe]

I looked at it and it must be a GEM or another similar kit. The reed case bolts where the intake would normally mount, I thought it was original since it's so clean and the fins hadn't been ground to fit it. Also the carb to airbox boot looks stock and I'd have thought it would have been shorter (I have an extra airbox and boot for a bike I've yet to pickup).

Anyone have jetting specs for a 'Piner with a GEM kit? You'd think a reed kit would improve the low end over stock. I've never had the top-end off so I don't know if it's been ported which could be hurting the low-end. As I said earlier, it really hauls from mid to topend.

Dang, now I want to tear in and see what's inside this thing. This is my first Penton, haven't ridden it much and am still learning. I'm fairly certain the Bing size is stock and I know the jets in it match the manual.

 

[imported_n/a]

Frank, I put a G.E.M. reed on my '73 Jackpiner in the spring of '74.  Before I had a chance to get it sorted out, the long-travel '74 Jackpiner came out and I sold the '73 and bought the '74.  Never even changed any jetting.

All I recall about the reed was that it was an easy bolt-on, except for drilling the holes in the piston.  Sorry I couldn't help.

Glenn

 

[john durrill]

Frank,
 if the reed on it is for a 175 , its too small for the piner. dont think you will ever get it running right. Try and find one for the 250 .The one gem made for the piner was not near big enough. It chokes the motor down. I did 2 for people one back in the 70's and one in the early 90's warned both that it would not run right but was told to add it anyway.
 The one for the 175 sold by Gem is about the same size we used on a 100 cc super rat Hodaka. We did many reed conversions on Hodakas , but went up 4 mm on carb size and added two boost ports in the rear  on them.
 The 175 flows a lot of air through the intake and needs a much bigger reed cage to not restrict the air flow into the engine.
 John.

 

[Frenfroe]

John, how would I know? The yahoo/hodaka group message board said the Hodies use a 613 Boyesen from a 125 Husqvarna.

I sent the specs from the reed in it to Boyesen and they said a #612 matches my reeds. This is a pretty big reed set which goes in a 390, 420 and 430 Husky.

What did the 250 GEM use?

 

[john durrill]

Frank ,
 That i cant tell you. its been too many years. but in the last POg news letter there is a guy running a 250 with reed in mx. he might know. there should be a # or model on the reed housing.
 it sounds like yours is big enough from the other models it was made to fit on.
 If someone modfied the ports that could give you  the problem you described.
 we went with a 30 mm bing on my sons piner and it runs clean but has a big hit when it comes on the pipe.
 I am working on a 30 mm lectron on my 175 and it seems to have tamed the hit and spread the power a bit. wont know for sure till i get it in the woods for a few days ride.
 we ended up gearing Peters down to make it better in the tight and slow stuff. it still has plenty of top end  speed like that.
John

 

[john durrill]

guys ,
 please post any info you have on reeds kits ( model #'s , sources , etc. )
and carb and ignition settings. I will post it on a web site in folders so we can use it as a library. I know it would save us all a lot of grief sooner or later.
Thanks,
John

 

[Larry Perkins]

Thank you John.  So much of that gets discussed again and again.  That will be helpful and informative.

 

[Frenfroe]

Ok, I couldn't stand not konwing what's inside this engine. I took off the top-end last week and found some obvious porting which explains the lazy low-end. The crank and bearings are fine. The timing check as Larry suggested was within specs. The carb is the stock 30mm with standard jetting. I checked the bore clearance and it's on the stock bore and clean and tight but the rings were worn too much (wider exaust and transfers?). Thanks to Al I'll have a new set shortly. I can't wait to get it back together with the new rings and reeds and see if it's any better. At least while it's been down I got the lights up and running. I gotta stop wrenching and get more saddle time in. My first enduro in 23 years is in 3 weeks.

By the way I made a map of the port work and will get around to measuring everything sometime and compare it to the Carl Cranke 250 mods. It looks to be similar to his port map in shape at least. Anyone have a stock cyl to compare it to?

Frank