Suzuki 2 Strokes

My bad, I made an assumption without opening up each of the pic's ... nice bike for sure!

Guys,
Chris forwarded to me a different view of the squish head insert. We can use varying thicknesses of copper gaskets which can alter the squish gap (and hence CCR) anywhere from 0.85mm (CCR 7.17:1) to 1.2mm (CCR 6.67:1). The gaskets are manufactured by Cometic (one of our sponsors) here in the States. Cometic has been around for quite some time and is a leader in gasket technology. They have the capability to make any gasket size/type from an array of different materials for most anything.
Ken

I'll plug our sponsor Cometic here as they are an absolutely amazing firm to work with. I forgot to include this pic of the "CARE package" I sent Chris with the new 5-port barrels, threaded couplings and some of the gaskets Cometic makes for us. Also, in this picture on top of the barrels, you can see the special threaded couplings with o-rings we use to seal the stud corridors when assembling the top end. We also have redundancy in the sealing of the top end end as Allen created some press fit sleeves inside the corridors to seal off the Tx & Ex passages ... belts AND suspenders!
Cheers,
Ken

SpecialK wrote:My bad, I made an assumption without opening up each of the pic's ... nice bike for sure!

Hey Ken - I have a set of the water cooled TR500/XR05 barrels. Link to pictures here:

viewtopic.php?f=2&t=263&p=75572&hilit=t ... ers#p75572

Supposedly good for 80hp but Suzuki cheated by moving the transfer ports to 9 and 3 and making it a siamesed cylinder block. This requires modifying the crankcase as well. Pete O'Dell was working on making clones of these but I do not know how far he got with the project.

Jim

Jim,
Hello to the Garden State from the Green Mountains! I remember seeing that barrel set a while back when you first posted it ... Precious metal there for sure. We are currently in the historic Period 4 class in our association and if we were to migrate to a circa 1974 w/c top end, we would then have to jump to Period 5 which brings in a whole new set of models which are more advanced both in engine and frame/suspension. It would also be a ton of work retrofitting that with the crankcase mod's, finding the head for it, a period specific radiator, etc. Our plan is to stick with the a/c version and get what we can out of it. Thanks for bringing that to our attention. It's a museum piece!
Ken

SpecialK wrote:Jim,
Hello to the Garden State from the Green Mountains! I remember seeing that barrel set a while back when you first posted it ... Precious metal there for sure. We are currently in the historic Period 4 class in our association and if we were to migrate to a circa 1974 w/c top end, we would then have to jump to Period 5 which brings in a whole new set of models which are more advanced both in engine and frame/suspension. It would also be a ton of work retrofitting that with the crankcase mod's, finding the head for it, a period specific radiator, etc. Our plan is to stick with the a/c version and get what we can out of it. Thanks for bringing that to our attention. It's a museum piece!
Ken

Hello back to the land of maple syrup, Ben & Jerrys, and the Von Trapp family!

I had mentioned the cylinder in case you had a desire to study the porting. Pretty sure I could talk the family into a weekend trip to Vermont if so! What organization are you racing with? USCRA?

Also if you are making a list of interested customers for cylinders, pistons, & heads please add my name to it as well.

Jim

It would be great to get a 3d scan of the water cooled cylinder block so one could be reproduced out of a block of Aluminum

What sort of flow work have you done to the top case ?

Hi Jim,
The build that we are presenting in this forum is raced in Western Australia primarily in the HCMC-WA association. I am starting to work with Pete here in New England on his T500 build and I believe he mentioned that he races in Canaan, NH and Louden, NH in the AHMRA (not sure on the acronym). I think Pete mentioned that he has raced in NJ as well on occasion (different bike) and that he needs to leave early to those events to give him time to get through the Gov. Chris Christy Commemorative Toll Both lol. I think the w/c variants of the TR500 still used a 136mm conrod length ... is that correct? If so if you were willing and had time to measure the port timings on one of the barrels and pass that along to me it would be greatly appreciated as I always like to compare notes. As far as a list of providing components from our build to interested parties, we haven't yet entertained that thought. I believe it would be possible to create G-Code to CNC fab the heads, as far as the pistons are concerned we can PM on that but the barrels are a labor of love which I do by hand and I'd have to think about how to be compensated for that effort. But first before we get ahead of ourselves, we need to sort this motor out. On another note, have you run VM38's on your T500? If so, might you be willing to share your jetting with me as we are getting ready to migrate over to 38's from 34's. Thanks!
Ken

SpecialK wrote: On another note, have you run VM38's on your T500? If so, might you be willing to share your jetting with me as we are getting ready to migrate over to 38's from 34's. Thanks!
Ken

Hey Ken - I have not run 38s on my T500 but I know Kris Larrivee ran them on his. He left T500s behind a while ago and recently switched from roadracing to hares scrambles in 2016. I'll PM you the contact info I have for him and you can see if he remembers what he was doing for jetting and also see if he even wants to talk about it still.

Jim

Geoff,
I wasn't able to attach my chart in the PM (you'll have to tell me how) so I'll post it out here (sorry Chris). When I get thinking about a subject, I can be a bit like a Terrier on a pant leg! So I put a little math together to at least show you the differences between two totally made up 38mm potential needle/needle jet setups wrt the flow area through the needle jet as a function of jet needle position. This chart by no means tells us which is correct but it does point out the differences between the setups ... interesting if not anything else. You can see that the two setups nearly flow identically through the first 30mm of needle movement with the red having a slightly higher flow. At the 30mm point, the 6DP17 makes a significant increase in flow change but meets up again at 40mm ... then the 6DP17 takes off again with anywhere from a 0.25mm2 to 0.5mm2 (ish) increase in flow all the way to full open (60mm). There are so many different needles out there and there could be multi setups that work as it's a bit of a black art. The dyno tells all for sure if you have an experienced carb man to be able to read the tea leaves. The blue line (6PD17-R2) was taken from the Ozebook website which cites this as being the factory Suzuki TR750 jet needle/needle jet configuration for VM38. I do not know why there would be a difference between a TR500 & TR750 38mm setup unless one was air-cooled and the other water-cooled ... temperature always seems to muddy things up!
Ken

Hello Ken,

Thanks for posting that data. As I said in the PM I seem to have become somewhat muddled with the stock set-up of the VM38s, even if they were purchased as a matched set to TR500 spec. according to the Mikuni main agent. The needles are certainly what Mikuni would provide with a stock VM34 and I have verified this from a couple of sources. I am going back to the distributor to see if they will give me their TR500 data, because I don't think that is what was originally supplied to me. My fault at the end of the day as I should have stripped them down when I first got them to verify they at least contained the same set-up (which they didn't )

I'll get back to you when I have some definite news.

Cheers Geoff

Seeing as we are now migrating to VM38 carbies on Chris' bike, I thought that this post would be relevant to this thread. In my quest to try and vet the initial 38mm setup, I thought I would compare the VM34 vs. VM38 fuel flow area between the needle and the needle jet wall as a function of needle position (throttle opening) and then compare that to the air flow increase of the two venturi diameters. Our VM34 setup which runs great uses the Q0 Njet paired with a 6FJ6 needle. There is no new discovery here as this is the factory setup in the 1972 TR500 factory bulletin. The NJet and needle combination I am choosing to try initially for our VM38 setup is what was published in the Ozebook site for a factory TR750 and that combination is R2 x 6DP17. So starting off, I calculated the difference in venturi flow area between the VM34 (907.46 mm2) and the VM38 (1133.54 mm2). The net out of this is that the VM38 venturi is ~25% larger than the VM34. This means that the 38mm venturi can source 25% more air than the 34mm venturi for a given partial pressure within the motor. Next are the published differences in cross-sectional area within the needle jets. The Q0 is 5.723 mm2 and the R2 is 5.980 mm2. The Mikuni needle diameters are characterized by distance from the top of the needle in D1(10mm), D2(20mm), D3(30mm), D4(40mm), D5(50mm) and D6(60mm). These two needles are 62.3mm long. The table below displays both needles by diameter at each interval, needle area at each interval and the amount of "flow area" between the needle & needle jet at each interval. Also the difference (Delta) in flow between each setup in percentage at each interval. The average ratio of all of the deltas along the needle is 1.281% which means the VM38 needle/Njet combination can source ~28% more fuel at any point within the total (needle controlled) throttle range versus the VM34. This coupled with the fact that the VM38 venturi is 24.9% larger than the VM34 plays nicely into a matched percentage increase in A/F in the VM38 which would be expected. The fact that these two independently derived values are nearly identical (25% vs. 28%) and the fact that each setup is factory documented gives me a good feeling that this is a good setup to start off with! We will be giving this setup a shakedown on Aug. 9th at our next tuning day. I will post our results from that effort.
I am probably full of beans!
Ken

Just in case you havent been to this site http://www.ozebook.com/compendium/t500index.htm" onclick="window.open(this.href);return false; .

Dave,
I've spent alot of time on this site over the past few years as Murray has done an amazing job of pulling of of that information together. This is where I got the setup for the TR750 VM38 jetting. We will see how accurate it is with our bike!
Thank you!
Ken