Thanks for posting info.
Next time you do a warm reading and of course have spare plugs add a cap full of oil and get two numbers. The first right after and do one more after rest guage. That would be for me to enter into spreed sheet that has your name on. It. Also sounds like it does not have much over rev . Should be able to be bumped to at least 7400 pipe temp will pull it there. Do you know if it's. Torque pipe or rev. ATVR/ power pros or Marv's. It makes a difference. Long or short silencer.

Any way enough questions have fun enjoy it a little and worry about gearing later.
Thank you taking time to do the work.

To answer; I'm not really sure which pipe this is. Can you tell from one of the pictures from page 3/4? Do you have pictures of the few you mentioned? There are no markings/numbers on the expansion/silencer anywhere.


So the good and bad from the past two days. (mostly good).

The good was, this machine ran fantastic all day! No major issues to speak of. Got tons of compliments on it. This thing really SCREAMS from 1/2 to full throttle. At the 1/8th mile I won some and lost some. I'd say anything sport with over 250cc was able to beat me; but I beat a KTM200, a WR250, and came close every other racer. This machine is fast. REALLY FAST. Much faster than I had imagined it would be.

I put about 4-5 hours on it and burned 10 gallons of C12


DurhamTown is a fantastic place. We camped out and had 2 full days of riding.

Now for the bad... I think the head gasket may actually be leaking but I'll run some tests to be sure. While the radiator was cold this morning I popped the cap to just take a look - and I noticed a non-stop stream of bubbling while the Engine was cold and idling. I was very sad to see this; but I DID re-use the old head OE head gasket without anything to help it hold. I did not shave the cylinder nor the head either - but I did of course clean them up very well on assembly. The gasket was new looking and I didn't have a new replacement and so I used it. Bummer. After seeing the bubbles I checked compression and it was still 180 so its either not a significant leak or its leaking air bubbles in from somewhere else - Hope not. The Engine is not ingesting coolant from what I can tell. I will be draining the balancer oil to be sure no coolant got in there. Its 50/50 Prestone/Distilled. Retirqued tge Head but the nuts didn’t move and no help. None-the-less I ran it for the entire day even with the bubbling as there was little I was able to do to fix it at the place. I did not check it more than once either because the machine was hot all day. I plan on installing an Autometer water temp gauge before the next ride. I also plan to run some vacuum testing on the cooling system to see if it will hold vacuum or not. I was planning to remove the head after today's rides anyway to check health of the piston/walls anyways, and so I'll probably just go ahead and order a new copper head gasket.

The only other issue I had was with one of the axle CV boots. Seems the one on the clutch side's clamp wasn't tight enough, and so about 2 tablespoons of grease spun out. Some of it probably slipped the belt/clutches but I didn't notice. No biggie.

Jetting. I need to do some research on brand conversion. I ended up with 48/1370(Middle)/152 jets, but the 152 jet was not a keihin - it was an EBC. See, Durhamtown has lots of jets in their pro-shop, but there are all EBC brand. Since I knew I needed to tun this thing and didn't have what I needed, I decided to run what Durhamtown sells; and BTW they DO let you trade-up your purchased jets with another size if the first size you buy isn't right - so I gave it a go and I'm glad I did. I'm not positive of the conversion but what I can say is, the machine ran GREAT with a 152 EBC main, but then noticeably worse with a 155 Keihin main. I did not have a chance to try a 155 EBC main but I did get one before I left to try and compare with the 155 Keihin another time. EGT was never more than 1100F, and the probe is like 5" from the piston. So basically I may try the 155 EBC that is IF I still have this PE carb on here. I did source a PWK39 which I plan to install with dual stage pre/post air filters with a modified airbox lid soon - which means jetting will have to be re-done from base-line then.


RPM. This one kind of stumps me. No matter what I did, my tiny tach always showed the same PEAK rpm of 7200. I wasn't watching the tach all the time - barely ever - but it does show me peak RPM of the session on Engine shut off - 7200 EXACTLY. Not +/-10 or anything. Always exactly 7200. I'm almost thinking either the rev limited modification I did didn't work, or just perhaps the PowerBlock needs a couple of weights removed. Any help here is appreciated.

Definitely a leaking head gasket. I've ordered a new one. Also ordered new air filters and items to make a nice large Pre-Filter out the top of the airbox.

I did pull the head. Piston wash to me looks good! Cylinder also looks great! No signs of seizures or detonation!

Check out the pictures!

So I ended up having both a 155 main Keihin and a 155 main EBC brand Keihin jet in my box. What I did was took one of my spare carb needles and slid each of the 155s onto the needle one at a time. i then lightly 'spun' the jet so that it would make a very minute mark on the needle (Indicating it's position on the needle). I did this with both the different brand 155 jets, and both marked in exactly the same exact spot.

So, the EBC jets may be OE Keihin jet equivalents.

I've begun mock-fitting my PWK39 carb the past two days. I got the carb used from a KTM off eBay and it arrived yesterday. I've ordered what I need to rebuild and re-jet it from jetsrus. During rebuild/purchase, I picked up a new intake, 16221-430-000 from Partzilla but could not use it for my stock carb at the time of rebuild. Its going to work well for this PWK39!

In rebuilding this carb, I've decided to base-line jetting at 48/175 (unless anyone has another combo to start with), but I'm getting a little stuck on which needle to use. I know needle selection is an art. I have a few needles; and it seems that my richest needle in my supply is one with a 3BC on it. I cant really look it up, but mic'ing the D1 and then the diameter at the tip reviles this needle is the richest in my collection. D1 is 2.66 which is a G needle.

I called Sudco to get some answers on some of my un-identifyable needles, but they weren't any help with them. The guy one the phone did say an FL400 with a PWK39 likes a E-series needle - I mentioned EEH or EEJ and he said yup.

Does this help you ?? (don't remember where I got it).

I've seen very similar in passing. It does help, and I can certainly easily measure D1, and L1 but I am stumped on how to accurately measure A and therefore I have 3 needles which I have no clue about.

Yes I believe I understand your problem now.
Check this page: https://jetsrus.com/a_jets_by_carbureto ... ikuni.html
I believe it answers your question. It appears that you take measurements every 10mm. Then armed with this info look for the needle number on the page.

Edit: opps - just noticed you are not looking for the mikuni needle numbers

I found this on Thumper talk but it is confusing to me. Maybe you can make sense of it.
https://thumpertalk.com/forums/topic/81 ... n-needles/
The pic at bottom of page may be the most help but not sure.
I started with this thread and clicked on the links in it: https://thumpertalk.com/forums/topic/65 ... eferences/
You can zoom in to some extent on your computer if you hold the ctr key and hit the plus sign.
Otherwise right click and hit save picture as. Then open pic and zoom manually.

I wish I knew which exhaust I had on this thing. It looks like a PowerPros stamped chamber, and its definitely a LONG silencer. I cannot tell if it is a Torque or REV pipe. My guess is a Torque pipe as its stamped? Not sure what the Marv's pipe looks like.



I took a look and its sort of confusing. Apparently given the measurement L1, the taper can be grabbed from this chart:



Then take the taper number which also corresponds to the MARK letter, and throw it into this chart here:




Basically I'm findingg the closest needle I have to what Sudco recommends is what I think comes out to an EEK needle - but it might be a chinesse knockoff needle. I went ahead and just ordered a genuine Keihin EEH needle just to be sure for $6.

You sticking with the 9 slide?

As of now, yes because replacement slides are a whee costly and not sure what is best.

Cool can't wait to see how the low end comes out. If can't correct with pilot go to a 6. Much richer.
This will fix idol circuit if you have to.
With the now lower velocity may work ok.

Like the way you work, pretty cool read.

Assuming the #9 slide is going to add air, what pilot jet do you think this may need? Theres a 48 in there now but I have a bunch of spares. Maybe a 50 or 52? Largest I have his a 55. I'd rather not have to remove this carb often once its installed; and the pilot jet can be tricky since the bowl has to come off.

In order to remove the carb, I'll need to remove the silencer, fuel line, and carb top every time to access the pilot. The main jet is much easier to change while the carb is still installed.

Thanks

If I was to guess because that is what it would be I would say one to two larger as long as it can idol with out more than 2.5 turn of air with out loading up. We're your may find an issue is low speed throttle. It will tend to load with too large of pilot jet and too lean of slide.
Again just a guess. Just thought I would share in case you run into an issue with idol circuit and off idol. You will know pretty quick if it does not respond off idol or cruiseing slow and get into it. Do not want to go lean on needle to compasate and run into an issue. Just food for thought.

Your E choice I like. I run an EEG. I use a low velocity set up so the G worked well for me.

Look forward to your results. It will be valuable info for others wanting to use ktm carbs. There should be an abundance of them shortly. Ktm I do believe is switching over to Mikuni. Most have 9,s

We should send H an email asking him to move into tech section. Tons of good info on this post. It your post so it should be your choice. I have most logged for future reference.

Hey Adnoh / Folks,

I did send a message @Hoser to move this thread to somewhere like projects area, but he never responded.

The past week, USPS has really put a fork in my side. Seems they lost three orders on me. Jetsrus order is MIA, UMI filter is MIA, and the new radiator cap is also MIA. Tracking on two of the three keep repeating themselves. UHG!

SO I did go and install an Autometer water temperature gauge, and am very close on getting the PWK39 installed, as well as the new airbox/filter setup. Just waiting on parts!

I put a new OE head gasket in modified to fit the 81.5mm bore. The old head gasket was defiantly a goner and I should have had my head examined the first time I re-used it. Along with installing the new gasket, I did remove all the studs and cleaned up both sides very carefully with some flat-block 2000 grit wet (With WD40) sandpaper; stuffed the cylinder side with paper towels, and cleaned it out good as to not drop anything down into the new Engine. Now hoping the head will stay put on this Engine for the season or more :)

I also replaced the front wheel bearings and seals; and while in there adjusted the front brakes yet again. The left rear tire lost air pressure again - I took a moment to check - and noticed both the rear tires were actually 15 years old. While they did have decent tread; they were probably time-bombs. So I got a good deal on some brand new ITP Holeshot tires size 22x11x10, which was a nice surprise when UPS delivered the day after I ordered them from a couple states away (Did I mention USPS SUCKS!) Mounted and ready to go. BTW I cant say enough good things about the Harbor Freight Mini Tire mounter. Works great and its now U-Bolted to my trailer's tongue.

https://www.harborfreight.com/mini-tire ... 61179.html

The last thing I did today; which won't actually affect me for several weeks - is I got a new VP racing VP110 54 gallon drum in exchange for my old C12 drum which was emptied into a couple last fuel cans. I couldn't pass up the price/deal as it was saving me almost $250 bucks off a similar sized C12 barrel. I figure in the jetski world; most run either one or the other without any noticed difference; so I hope it works per the price advantage. The biggest thing I notice about C12 vs VP110 is the allowed/rated CR. C12<15:1 while VP110<13:1. I'm not really sure how much truth those numbers hold but will see. I'm figuring wtf on VP110 at 13:1 only? Sheesh... I know people who run that CR on 93 octane pump gas. The VP110 has got to handle more CR than rated especially in a 2-stroke dynamics! Its only 1 octane less than C12. Anyways; I'm not going to bust open the VP110 barrel for a couple weeks because I actually have 10gallons of C12 left in all my gas cans (Which is about 1 weekend of riding one or the other fun-toy). Oil mix 40:1 with Klotz R50. I also have a gallon of Klotz SkiCraft but dang that stuff looks/smells/is different/thin/pink. Not sure if I should use the SkiCraft in anything. Maybe I'll sell it to a friend. I'm sure its fine but I like my R50.

Lastly, well; check out the picture. Last ride I found my pilot extremely fast on the woods trails. Nothing ever came up on me; and I grew tired and bored of following slow people at Durham Town. Its actually a lot louder than it looks. Hope you like

I seem to have a cooling system issue here. I was able to button everything back up and start it, and I noticed the bubbling is now worse with the new head gasket compared to the old one; in the radiator when running/cold/idling. There is definitely something going on and I'm not getting the greatest of feelings over here.

I'm thinking there may be a leak between the cylinder sleeves or the cast cylinder walls. This sucks.

I did pressure test the whole system from the top of the radiator to +15psi, and then -27 in/HG, and both held very well with practically no pressure drop. Not sure what is up? Maybe only when the Engine is running; extreme combustion pressure is getting by somewhere? I've got the combustion test fluid to test it out next time I start the Engine.

Sheesh.

Before taking it apart let's discuss a few things.
We know it had coolant issues when you bought it.
Since it has bubbles in coolant can we assume the pressure at or above ex open is causing it?
Either combustion.pressure or swept volume issue.
So is the head one piece or two pieces with o- rings?

What I do altering a cylinder is high pressure the cylinder with the head on it with gasket choice.
I also check one that has an issue by leaving the head on and pulling the cylinder with head intack. Base gaskets are cheaper any way.

The I hook up hose in a by pass with a It fitting to my compressor. This way I can pressurize the cylinder.
Then I pore a water and soap solution in the head just past the gasket and start adding pressure. If the head is leaking it will start to bubble. If not add a little more and more untill you reach exhaust port. If it's a cracked sleeve it will show up. The using your exhaust and intake block off plates you can start to fill it more to see if it's in the exhaust then intakes.

If your leaking in the head area. Clean up and add fluid I. Combustion chamber working towards gasket.
I think you get the gist of it.

Then you can fix and reteat. Once fixed slid head and jug back on with new base gasket and run.

I have had issues after porting that I opened up a pocket which failed high pressure air test. Easy fixes.

Remember higher pressure for bench only not with clinder on machine. And yes it can be a little dangerous so be careful full and use new hoses not your good rad hoses. I put up to 120 psi. It usually will find it. Do go that high unless you have to. Then use you compressor knob to depresureize slowly. And don't leave it on to long. Go up look for bubbles and go back down. Once you isolate you can use only what you need with spray bottle to spot. Mark and fix.

I did some video a few years back I dig up and post for you if not clear.


There has been post where the sleeves crack after over bore for some reason.

Cooling jacket aside, I did not like how the 50 pilot jet was popping off at idle, which btw the idle screw spring has been clipped, screwed all the way in, and the air screw is at 2.5 turns. The Engine was running very rich with a 50 pilot. I closed the petcock and let the carb drain a bit so that I could service it without spilling tons of fuel; and as the carb ran a bit dry the Engine rpm did pick up quite a bit before I hit the kill switch - indicating very rich idle. I dropped to a 45 pilot and it got better but more or less similar to the 50 pilot. Now I'm thinking about dropping to a 40 pilot, or dropping the needle one position from the middle, or maybe this #9 slide really is not right.

I did pressure test the whole system from the top of the radiator to +15psi, and then -27 in/HG, and both held very well with practically no pressure drop. Not sure what is up? Maybe only when the Engine is running; extreme combustion pressure is getting by somewhere? I've got the combustion test fluid to test it out next time I start the Engine.

Failing the exhaust gas test, I'll drain and pull the whole cylinder with head installed, and run high pressure testing. I'm thinking I can just do it in a bucket of water.

If it is leaking between the sleeves or cast, how do I fix that?

The head is a 2-piece design which only has O-Rings near the spark plug - otherwise it uses a stoke/style head gasket as there are no grooves for o-rings around the dome nor head shell.

Havnt played with 2strokes in a long time.

Does the bubbling definitely mean a combustion leak somewhere?

Could it just be an air pocket bubbling out of the coolant system?

Does it overheat when running?

It really should not bubble. I mean, I could see the system needing to be burped a bit upon flush and replace, but not a stream of bubbles. Its strange here. When starting the Engine, it takes only about a minute for the radiator cap to come under pressure, and then it starts bubbling out of the overflow - spewing some antifreeze out of the system. Its not normal. It has not overheated for me as far as I can tell.

But then again I'm baffled by my pressure tests to +15psi/-27in/hg holding fairly stable.

I'm going to get the exhaust gas tester later today from auto zone. Failing that test I'll pull the cylinder with the head attached and perform some high pressure tests per Adhon above.

If there is a sleeving leak anywhere my only home remedy would be to try to locate the leak and fix it with epoxy. I found QuikSteel brand makes an ultra high temperature epoxy good to 2500F, called Blue Magic QA Metal repair. Seems people have had it work on exhaust manifolds, and it should be available locally:

https://www.autozone.com/sealants-glues ... 515553_0_0

Did you run it without the cap until it was up to operating temp?

that's what i always did with my bikes. Don't know if its right or wrong but it worked.

Its that polaris fuel pump being rejected!

Thanks for the words.

So today I feel better, but am also a bit stumped as to what is going on. Perhaps it really is cavitation at the pump; maybe I'll find out at a later point. The good news is, exhaust gas does NOT seem to be getting into the coolant as I thought. The block tester passed; fluid stayed blue in the tube. Now, today there was much less bubbling than yesterday, but it was still bubbling. Im not sure why because it did not fail the test? Hope the block tester is accurate. Perhaps there really is just a bunch of air down there. Would be nice.

In better news, I began trying to tune the PWK39 some more. I thought the 45 pilot was still too rich so I dropped to the next size I had - a 35 pilot. Yes I know that's probably way low, but it seems to be working best right now with 2 turns on the pilot air screw. I'll have to monitor idle down especially when I get the main jet dialed in, which I have a 170 main in there now. Needle EEH on the middle clip. I was also thinking of going back to the 45 and dropping the needle or dropping main jet, but really need to road test it now.

I'm headed to a local place I've found jets to pick up a 38 and 40 jet - that way when I dirt test this thing I'll have both high and low ranges in my collection to swap. Also I figured out a quick way to change pilot jets and so much rejoicing, and I found a spare DEE needle which may come in handy. It should be richer down low and slightly leaner up top. Maybe it won't work.

Got my dual/prefilter today finally. Thanks USPS. All orders came in after 10 days

Block tester

Here is how it works: https://www.youtube.com/watch?v=X4mtnzAameI