Post by Chuck78 on Nov 25, 2019 1:33:57 GMT
I was hoping to find any detailed info on more modern flatslide carb swap upgrades to our PE's. I have an '88 KDX200's PWK35 flatslide that I snatched up in the event that someday I may find an 86-88 KDX200, 86 and 87 still ran the older Mikuni roundslide carb. It may go good on a PE as well? 88 was a rare KDX carb year, only year of that handing on the flatslide, 1989-2006 had mixture screw and choke lever on the other side (water cooled era). I also recalled reading on the old PE Yahoo Group of member Alex's PE400 which he upgraded to a Lectron flatslide. Lectron may be the only marginally-legal carb that I could run if vintage racing my PE's or street bikes, as it was the first flatslide available, and the only one available in the late 1970's/early 1980's...
Does anyone else have any firsthand accounts of good carbs to use, what was needed to fit them, what bikes they are on now, and what jetting was needed (with your location and altitude mentioned)?
Here is what Alex had to say:
Those who read my posts over the last 7 years will recall I have had trouble with fine tuning the Mikuni 36mm Round Slide. It has always given me hassles no matter how many hours and jet changes and/or adjustments I did to it.
So after the last ride which was a desert rally of around 160KM, I decided to do a simultaneous top end rebuild and fitment of a Lectron 36mm flat slide carb. I read the article on the Lectrons in the latest issue of VMX magazine and the lack of jets made it also an attractive choice. The article was timely as I was in the market to replace the carb.
The top end was also just fitted with a Ron Anchak 1mm oversize piston and the barrel was the one I bought in a pile of parts which had extensive porting work some 4 years ago I discussed back then. I also have fitted carefully cut Carbontech Reeds with the reed stops adjusted at the maximum 10mm opening. The pink compound you see at the pipe and flange joint is CRC Maniseal exhaust cement. Necessary to get a good tight seal in that area, that stops black oil being sprayed and dripped onto your clean surfaces..
The swept volume of this engine turns out now to be just under 420cc. Anchak has pistons up to 2mm oversize coming soon.......I do suggest to buy a set of oversize say 1.25mm rings off Ron when buying the 1mm piston as sometimes these may be necessary fitment depending on the reboring. The cylinder was correctly bored to meet the specified piston to bore clearance of 0.064mm, but the rings needed to be slightly tighter. My 1mm just measured 0.65mm ring gap cold as when the engine gets hot the ring gap decreases. I would have preferred a tighter gap hence the need for the oversize rings.
So after the last ride which was a desert rally of around 160KM, I decided to do a simultaneous top end rebuild and fitment of a Lectron 36mm flat slide carb. I read the article on the Lectrons in the latest issue of VMX magazine and the lack of jets made it also an attractive choice. The article was timely as I was in the market to replace the carb.
The top end was also just fitted with a Ron Anchak 1mm oversize piston and the barrel was the one I bought in a pile of parts which had extensive porting work some 4 years ago I discussed back then. I also have fitted carefully cut Carbontech Reeds with the reed stops adjusted at the maximum 10mm opening. The pink compound you see at the pipe and flange joint is CRC Maniseal exhaust cement. Necessary to get a good tight seal in that area, that stops black oil being sprayed and dripped onto your clean surfaces..
The swept volume of this engine turns out now to be just under 420cc. Anchak has pistons up to 2mm oversize coming soon.......I do suggest to buy a set of oversize say 1.25mm rings off Ron when buying the 1mm piston as sometimes these may be necessary fitment depending on the reboring. The cylinder was correctly bored to meet the specified piston to bore clearance of 0.064mm, but the rings needed to be slightly tighter. My 1mm just measured 0.65mm ring gap cold as when the engine gets hot the ring gap decreases. I would have preferred a tighter gap hence the need for the oversize rings.
(CLICK PHOTOS FOR LARGER VIEW)
In the the photo’s you will see the finish I have selected for the head and outer engine cases. It has been hydroblasted, some places like in the USA call it vapour blasting (never sandblast these parts!) and coated with VHT Hi Temp Flame Proof Clear. The central case is just painted with VHT Black Barrel paint. This was inspired by seeing de Witts RM465Z at Farleigh Castle that had a similar combination of choice of finish and I liked it so much I applied it to the PE.
www.thehydroblastshop.com.au/gallery4.html
www.yamahait.com.au/forum/index.php?topic=10762.0 I used this local guy.
I have also then sanded and polished by hand (after painting the hydroblasted barrel with VHT Black Barrel Paint) the outside edges of the fins to give it a unique look inspired by an XT500 I saw recently. All the other parts around the engine, including every nut, bolt and screw, and rest of the bike have been zinc plated (exhaust was previously ceramic silver coated). It is my interpretation of what the PE should have looked like from the factory in ensuing years. The KDX and IT during that era both had this mass produced boring all black finish on everything to their bikes so it wasnt just the Suzuki’s.
The people at Lectron USA were excellent, I dealt with Kevin Gilham whose is the President of Lectron at all times. After giving the measurements to Lectron they machined the spigots exactly to the same dimensions of the Mikuni, including overall length, so the carb just fit in like stock. Carb, machining and new throttle cable to fit my Magura (plus special tool for tuning the jet needle) was A$540 (USD$490) delivered in 9 days after paying for it.
www.youtube.com/watch?v=boa_TvDFT24 How to tune the Lectron for 2 strokes.
I purchased the extra Terry throttle cable with the kit as Lectron did state that you need a new cable, and fitted it with ease, but thought maybe the stock cable would fit after looking at the job as the only difference is the slight size difference of the end alloy crimp that fits into the carb slide. A smear of solder around the stock crimp (if at all needed) would enlargen it to fit the slide and stop it from coming through the hole.
After the photo’s were taken I have also rerouted the cable between the tank and frame tube so that it now has a more direct vertical entry into the carb slide.
Once everything was installed (new piston/barrel/carb) the bike started 2nd kick. It steadied into a smooth idle after adjusting the idle screw in. I ran the motor at or near idle for about 8 minutes on the stand and then turned it off as in normal practice after a rebuild.
On the weekend I took the bike to a nearby state forest where I filled up the tank and took it for a ride. It started first kick off the trailer and idled well after immediately pressing off the choke. I let it warm up as I got dressed in my gear and then took off down the road where once the engine got to operating temperature it commenced detonating and the reeds began to flutter and spit as it did before. I knew it was lean and I came to the conclusion later that Lectron adjust their carburettors lean from the factory after giving them all the bikes and usage data.
I took off from about 200 Metres above sea level and the bike ran progressively better as we climbed up to 800M high up the Black Range so it was running lean. The bike didnt have much acceleration or performance either.
I rode like this carefully around the forest loop for some 20KM before returning and then proceeded to take the slide out and turn the fuel metering rod in to richen it (with the special tool included with the carburettor). I took it in half a turn as the running was a long way from ideal. As soon as I let the clutch out the bike was different, it accelerated away like never before with no detonation during acceleration or reed flutter when backing off the throttle or going back to idle speed. It was very different, even the way it sounds, and I was pleased but couldnt really run the bike hard as it was still new.
Once I got back down to lower altitude the bike started to progressively detonate again slightly and reed flutter a bit, so back at the trailer wound the rod in again another half turn (they recommended quarter turns at a time!) and that fixed it completely after going for another ride. So one full turn in from supplied position. The bike ran so much better that near full throttle was possible and I found that the top end was then somewhat lean as the engine revs “broke up”.
The Lectron comes equipped with an adjustable power jet to dial in the top end jetting. (you can see it in the photo’s between the airbox and carb body to the rear) So I just pulled over on the bike and just turned it with my fingers half a turn out to richen it and the bike straight away revved out cleanly. I didnt hold it open as the motor is new but shut it down as it hit high revs. I will turn out the Metering Rod perhaps another quarter turn in and the power jet also another quarter turn out on a future ride and see how it runs and I think that will be fairly ideal as you want to be on the part of richer rather than leaner. The day was quite cold especially at 800m where it was about 6 Celsius, foggy & wet so for warmer weather riding the settings I have now may be spot on.
I only used about a gallon of fuel for this first ride and need to get at least another full tank before I can start to ride it harder. Winter has set in here so may have to wait a while. The transparent plastic float bowl looks trick and many other riders (with new bikes) who crowded around when I pulled up to the bike unloading parking area commented on the whole bike and carb. The bowl doesnt have a drain plug and it is my practice to drain the bowl and tank after each ride, so to drain the bowl I tilted the carb 90 degrees and it drained out through the breather hoses. I had the slide out at the time so just drop the bike to the ground onto its side, after turning the fuel tap off, to drain the bowl.
In conclusion I wish the bike ran this perfect 7 years ago when I first got it. The stock Mikuni was definitely the limiting factor and the cause of poor erratic running. My KTM GS250 restoration project has a stock Bing fitted and once that is up & running will assess the performance and then might fit a Lectron to that as well.
If you are going to get a new carb then ensure the Lectron is on the short list.
www.thehydroblastshop.com.au/gallery4.html
www.yamahait.com.au/forum/index.php?topic=10762.0 I used this local guy.
I have also then sanded and polished by hand (after painting the hydroblasted barrel with VHT Black Barrel Paint) the outside edges of the fins to give it a unique look inspired by an XT500 I saw recently. All the other parts around the engine, including every nut, bolt and screw, and rest of the bike have been zinc plated (exhaust was previously ceramic silver coated). It is my interpretation of what the PE should have looked like from the factory in ensuing years. The KDX and IT during that era both had this mass produced boring all black finish on everything to their bikes so it wasnt just the Suzuki’s.
The people at Lectron USA were excellent, I dealt with Kevin Gilham whose is the President of Lectron at all times. After giving the measurements to Lectron they machined the spigots exactly to the same dimensions of the Mikuni, including overall length, so the carb just fit in like stock. Carb, machining and new throttle cable to fit my Magura (plus special tool for tuning the jet needle) was A$540 (USD$490) delivered in 9 days after paying for it.
www.youtube.com/watch?v=boa_TvDFT24 How to tune the Lectron for 2 strokes.
I purchased the extra Terry throttle cable with the kit as Lectron did state that you need a new cable, and fitted it with ease, but thought maybe the stock cable would fit after looking at the job as the only difference is the slight size difference of the end alloy crimp that fits into the carb slide. A smear of solder around the stock crimp (if at all needed) would enlargen it to fit the slide and stop it from coming through the hole.
After the photo’s were taken I have also rerouted the cable between the tank and frame tube so that it now has a more direct vertical entry into the carb slide.
Once everything was installed (new piston/barrel/carb) the bike started 2nd kick. It steadied into a smooth idle after adjusting the idle screw in. I ran the motor at or near idle for about 8 minutes on the stand and then turned it off as in normal practice after a rebuild.
On the weekend I took the bike to a nearby state forest where I filled up the tank and took it for a ride. It started first kick off the trailer and idled well after immediately pressing off the choke. I let it warm up as I got dressed in my gear and then took off down the road where once the engine got to operating temperature it commenced detonating and the reeds began to flutter and spit as it did before. I knew it was lean and I came to the conclusion later that Lectron adjust their carburettors lean from the factory after giving them all the bikes and usage data.
I took off from about 200 Metres above sea level and the bike ran progressively better as we climbed up to 800M high up the Black Range so it was running lean. The bike didnt have much acceleration or performance either.
I rode like this carefully around the forest loop for some 20KM before returning and then proceeded to take the slide out and turn the fuel metering rod in to richen it (with the special tool included with the carburettor). I took it in half a turn as the running was a long way from ideal. As soon as I let the clutch out the bike was different, it accelerated away like never before with no detonation during acceleration or reed flutter when backing off the throttle or going back to idle speed. It was very different, even the way it sounds, and I was pleased but couldnt really run the bike hard as it was still new.
Once I got back down to lower altitude the bike started to progressively detonate again slightly and reed flutter a bit, so back at the trailer wound the rod in again another half turn (they recommended quarter turns at a time!) and that fixed it completely after going for another ride. So one full turn in from supplied position. The bike ran so much better that near full throttle was possible and I found that the top end was then somewhat lean as the engine revs “broke up”.
The Lectron comes equipped with an adjustable power jet to dial in the top end jetting. (you can see it in the photo’s between the airbox and carb body to the rear) So I just pulled over on the bike and just turned it with my fingers half a turn out to richen it and the bike straight away revved out cleanly. I didnt hold it open as the motor is new but shut it down as it hit high revs. I will turn out the Metering Rod perhaps another quarter turn in and the power jet also another quarter turn out on a future ride and see how it runs and I think that will be fairly ideal as you want to be on the part of richer rather than leaner. The day was quite cold especially at 800m where it was about 6 Celsius, foggy & wet so for warmer weather riding the settings I have now may be spot on.
I only used about a gallon of fuel for this first ride and need to get at least another full tank before I can start to ride it harder. Winter has set in here so may have to wait a while. The transparent plastic float bowl looks trick and many other riders (with new bikes) who crowded around when I pulled up to the bike unloading parking area commented on the whole bike and carb. The bowl doesnt have a drain plug and it is my practice to drain the bowl and tank after each ride, so to drain the bowl I tilted the carb 90 degrees and it drained out through the breather hoses. I had the slide out at the time so just drop the bike to the ground onto its side, after turning the fuel tap off, to drain the bowl.
In conclusion I wish the bike ran this perfect 7 years ago when I first got it. The stock Mikuni was definitely the limiting factor and the cause of poor erratic running. My KTM GS250 restoration project has a stock Bing fitted and once that is up & running will assess the performance and then might fit a Lectron to that as well.
If you are going to get a new carb then ensure the Lectron is on the short list.
Kind Regards,
Alex D Vercion
Alex D Vercion
