PG Short Tuning.

[gsx600racer]

I finally had a chance to install my PG short on my Kymco II build.

The problem, it runs like crap till 6K rpm. Once it hits 6K it wakes up and pulls like hell.(the stuff iv seen in video's)
Under 6K, it sputters/surges and lacks power.

The current carb set up: 

OKO 21mm carb, Pilot 50, Main 115.
OKO 26mm reed block CT intake

UNI Air Filter(open foam)


Tried jetting up to 120 main and on the stand the revs did not want to get to 6K. 
Down jetted to a 110 main and it ran just about the same but did sound like it was running lean,(cutting out) at almost wot.

I followed this guideline for tuning the pilot(slow) jet. "It is important to adjust the air screw for the final setting after the engine is completely warmed up. The final adjustment should be between one and two turns out. If less than one turn, replace slow jet with a larger one. If more than two turns out, replace with a smaller one." 

I have not played with rollers/cvt because I assumed with the engine running like crap from idle to 6K, its more of a carb tuning issue.

I was running a 115 main with the Tecnigas Next-R and ran good and temps maxed in the 320-345 wot. 

Any thoughts ?

[oldgeek]

I know very little about pipes, but I can tell you my PG short is a straight through pipe with no cones. In other words it is not at all like a true expansion pipe. I have not had the opportunity to run it very much, but I cant see it being much of a performer. Yeah, I know some swear by the PG short, but I guess they know how to set it up correctly. Hopefully 190mech will enlighten us as to how the PG short can be a decent pipe.

I have been looking at one of the autotech expansion pipes, wondering if it is worth the $189. I would really like to have one of the over the top polini pipes, but it is hard to spend that kind of $$ on a pipe.

[190mech]

Sorry guys,I dont know a thing about the PG short,If y'all post some links,I can look them over and give you my worth...

[gsx600racer]

Thanks folks. I put the pipe on late yesterday evening and ran out of daylight. I have all day today to muck around with it and see progress I can make. Will try to come up with a way to record a video(while riding) to show what am describing above.

[birdman]

My pg short was the same way on my elite. Until i went lighter on the weights i went 8g weights to 5g weights, then that pipe woke the f up and then i saw what all the hype was about.

[birdman]

but exactly which weights you use will depend on what cylinder your running. I onky have experience with a pg short/ corsa combo. So maybe 5g may nit be the sweet spot for you.

[gsx600racer]

Well I spent the better part of the day trying to tune this pipe.

I tried everything carburetor related:
up-jetted main to 150 & down to a very lean 95(no effect)
same with the slow jet, lean or rich made no difference other than messed with idle.(ranges 52-45)
raised and lowered the needle, effected top end but no help on takeoffs.

Conclusion, my launches need to be @ 6100-6200 rpm where this exhaust starts to work with my cyl/carb setup. Any rpm below that is useless under load.

I am not keen on using heavier clutch springs to get to a higher launch rpm because of the taller gears iv installed. My clutch bell is already browning/bluing from of the heat of slippage. I am afraid the heavier springs will cause more slippage than what I have now. I might have to consider a different clutch setup.

I also tried this pipe on my Malossi kitted Kymco and had the same results. I am going to shelf this pipe for now till I build a l/c stroker engine(next winter's project)

[gsx600racer]

May 28, 2016 21:39:09 GMT -5 oldgeek said:

I know very little about pipes, but I can tell you my PG short is a straight through pipe with no cones. In other words it is not at all like a true expansion pipe. I have not had the opportunity to run it very much, but I cant see it being much of a performer. Yeah, I know some swear by the PG short, but I guess they know how to set it up correctly. Hopefully 190mech will enlighten us as to how the PG short can be a decent pipe.

I have been looking at one of the autotech expansion pipes, wondering if it is worth the $189. I would really like to have one of the over the top polini pipes, but it is hard to spend that kind of $$ on a pipe.

I was hoping you had some experience with this pipe. I was disappointed that this pipe has nothing to offer below 6000 rpm. With the taller gears and me being a heaver rider I might as well been riding a moped. I will say this, once this pipe/engine wakes up, it pulls hard and fast. The needle did past the 60 mph dot on the speedo by a few ticks and me not wearing a helmet I was not going to press my luck finding out how much more was there.(tires are starting to crack/dry rot on the bead) I might consider CVT tuning to get the engine/pipe to play well together but my goal was to have something that had some low end grunt to push thru the taller gears with me on it. 

[gsx600racer]

May 29, 2016 3:49:09 GMT -5 190mech said:

Sorry guys,I dont know a thing about the PG short,If y'all post some links,I can look them over and give you my worth...

Pipe brand name is Phongeer, they make a short and a long version. Hence the name PG Short/PG long
The short version is usually for mild builds where the long is for stroker/large cc builds.

Ebay link(where I Purchased mine)

[moofus02]

If it doesn't make power until 6k and you are trying to take off with lower rpm your clutch will slip. Before you shelf the pipe put some stiff clutch springs in it and maybe some lighter rollers. You have the clutch grab where it's making power won't slip as much as if you are trying to engage before it is in the power. If it makes power above 6k get the tranny tuned for the rpm it likes and the clutch engaging in the power. Tuning a carb off the pipe is a bad idea. You want to tune carb for the hit. If you tune the clutch and roller weight for what the pipe likes I doubt you will have the clutch heating problems you are having now and be much happier with the combo. 6k isn't that high of an rpm to be street friendly.

[oldgeek]

May 29, 2016 20:27:55 GMT -5 gsx600racer said:

I was disappointed that this pipe has nothing to offer below 6000 rpm. With the taller gears and me being a heaver rider I might as well been riding a moped.  

The extremely tall gearing may also be a problem. You might consider swapping the stock gears back in, and get the CVT, carb, and pipe dialed in. Then swap the tall gears in and see if they still pull.

[gsx600racer]

May 29, 2016 12:29:56 GMT -5 birdman said:

but exactly which weights you use will depend on what cylinder your running. I onky have experience with a pg short/ corsa combo. So maybe 5g may nit be the sweet spot for you.

Thanks for the input,

My build specs are here.

I like the pipe, just not happy with the performance under 6k rpm. I am running taller gears which does not help my situation.(slower takeoffs and more engine loading) As mentioned in pervious post, I really was looking for more low end torque to help pull the taller gears and my body weight. I really did not want to build a drag/high revving setup. I will be happy seeing 9-10k rpm with temps running in the low to mid 300's.

I am going to do some clutch shopping, I am running a almost stock clutch setup and need something that can hook up better and can handle the extra heat. 

[gsx600racer]

May 29, 2016 20:51:38 GMT -5 oldgeek said:

May 29, 2016 20:27:55 GMT -5 gsx600racer said:

I was disappointed that this pipe has nothing to offer below 6000 rpm. With the taller gears and me being a heaver rider I might as well been riding a moped.  

The extremely tall gearing may also be a problem. You might consider swapping the stock gears back in, and get the CVT, carb, and pipe dialed in. Then swap the tall gears in and see if they still pull.

I totally agree, think we had this convo back in the beginning when I first started this build. 

I know with the carb setup with the Tecnigas is almost spot on. I just was not seeing the rpms and the pull I was expecting with that setup.

As for the cvt(before pipe swap) I was pretty happy, was a little sluggish from 0-20 mph, once is got past the "tall gear" clutch slippage and clutch was fully engaged(no slipping) it hauled out pretty good. I was hitting just under 60mph on the speedo = probably as solid 55-57. I need to get an action cam and helmet mount it. 

I just haven't had the time to research a few options and to tinker with the toys.

Iv put my YMS V8 pipe back on vs the Tecnigas, reverted back to original carb/cvt tuning just to see if there is a noticeable difference. I did the break-in with the YMS but didn't do much "spirited" riding

[birdman]

I agree with moofus02 lighter rollers stiffer contra and heavier clutch springs.On my Elite Im running the same Corsa/ PG short combo you are with great success. Your problem is in the CVT Im almost sure of it. I had the same issue as you did when I first got my PG short, I resolved the issue with lighter rollers.

[190mech]

The tapered headpipe likely gives it the 'hit' everybody likes,,be neat to look at the insides with an endoscope...