slavens ported 500

[2premo]

I had a 87 430CR & my 88 430WR never pulled like the CR did. The CR was apart a time or two before I owned it but I never had a reason to open it up. Now my WR pulls like my CR did! I raised the exhaust port, cleaned up the transfers, & slightly flared out the top of the intake ports. She flat out rips now! Gently roll the throttle on & it's like a direct link to the back tire breaking loose! (or the front end lifting)

my '87 430 is slightly ported as in mostly the transfers and cleaning the ports in general, it pulls like a 500,,, seriously i have one to compare to

 

[troy deck]

very cool pipe premo, gotta love it when the big bores go hunting for some volume, pipes can take some interesting routes! yours looks to be tucked away from danger fairly well..too bad stuff like this is never found for sale.
also, the transfers are knifed, in a blunt way. he does them like a butter knife. thinking of building an engine around this jug, very neat to find stuff like this. thanks everyone for sharing.

sumpin wrong with the engine its on

 

[Nikel]

Hi Justin.
Could you make a paper copy of the ports on the cylinder?

Roll a piece of paper and put it inside the cylinder, tape it and take a pencil and run over the ports.

I'm thinking about doing some work on my engine this winter and it would be cool if I had something to go after.

 

[robertaccio]

I would simply call Jeff and ask him about it. easy as that. Im sure he will be more than happy to answer your questions as long as hes not up to his elbows in something.

 

[Nikel]

I would simply call Jeff and ask him about it. easy as that. Im sure he will be more than happy to answer your questions as long as hes not up to his elbows in something.

I didn't see the post about his youtube chanel untill today so I will send him a question over there.
I'm not sure what my phone bill think about long distance calls =)

 

[justintendo]

i could try it, probably wouldnt hurt to do anyway so i know.

 

[Nikel]

i could try it, probably wouldnt hurt to do anyway so i know.

That would be awesome.

I have sent Jeff an e-mail so hopefully we get some info from the man himself =)

 

[troy deck]

id pay for his work

 

[Nikel]

id pay for his work

It sure looks good.
But that is probably because you cant see any grindingmarks or anything.

Me and a friend are planing to make a new head design to the 500 this winter.
He is an old two-stroker guru and is one of the few who have got an 430 to backfire so hard that it sent him 2 meters above the bars and landed on his head in front of his bike.

It would be cool if I could make it to match this cylinder =)

 

[justintendo]

just advance the timing enough and run one size too rich pilot. its not hard to get a big 2 stroke to bite you. get the timing right (slightly retarded) and have it tuned properly, kickbacks become rare or sometimes completely gone.

 

[2premo]

my 87 430 had the timing at 1.9 back from 2.2
knife ported and clean up the horrible 80's castings
5000' jetted correctly all but 6th was a fight to keep the nose down
timing back where it was originally at 2.2mm BTDC and it kicked but did not make enough extra power to justify the hard starting
also its hard on the crank due to the abusive power cycle from being a little advanced, but it was tough on the kicker gears to boot

 

[Nikel]

just advance the timing enough and run one size too rich pilot. its not hard to get a big 2 stroke to bite you. get the timing right (slightly retarded) and have it tuned properly, kickbacks become rare or sometimes completely gone.

The flywheel had come loose so he had about 15 degree advanced timing.
But that is about 20 years ago now.

 

[justintendo]

my 87 430 had the timing at 1.9 back from 2.2
knife ported and clean up the horrible 80's castings
5000' jetted correctly all but 6th was a fight to keep the nose down
timing back where it was originally at 2.2mm BTDC and it kicked but did not make enough extra power to justify the hard starting
also its hard on the crank due to the abusive power cycle from being a little advanced, but it was tough on the kicker gears to boot

not to mention helping save the sidecases as well.

 

[Nikel]

I have made a paper template of my stock 500 cylinder.
So if you make yours and upload it as a pic we can sew if there is any difference =)

Edit:

Done some calculations/measurements now and the 500 is at stock more or less tuned around 9000 rpm.
But I don't expect that the pipe is tuned for that RPM.

I have to do some counseling tomorrow.

 

[Bigbill]

I raise, widen and arc the exhaust port. I lower the reed ports. Then knife edge and smooth out the transfer ports. I clean up and taper the reed section. Then I advance the timing a tad because of the port timing changes. The quicker the hot gasses can exit with a well tuned pipe the faster the fresh gas can be transfered into the cylinder. I install a reed spacer to give more room around the reed box area. She can breathe much better. The intake has more chee(flow)
Sort of speak. Everything works together.

I ported a 85 Honda 125cr and a 81 husky cr250 years ago. The 125 would walk away from the 250's and the 250 husky would eat newer 250's down the straights. Both bikes were very responsive throttle wise.

 

[dartyppyt]

I had a ported and carbed 82 Cr 430. I kicked it with a pair of work boots once and I laid on the driveway thinking that my ankle was broken. Come to find out that when it kicked back, it also took a gear tooth off the idler gear between the kicker and clutch basket gear. There was a guy in front of me that pulled the hole shot and we were going down a dusty straight. He had a new KTM 500. He said I hit him like he was sitting still. It hit my front brake cable and I flipped and took us both out. That damn 430 would climb a tree. That thing also kicked back once on a dead engine start Harescramble. The engine started backwards and when I let the clutch out, the bike went backwards and I went over the bars. It was hilarious. My neighbor ported it and spent like 40 hours inside it. So I am trying to match what he did.
I also want to play later with a VM carb to see if it acts like the newer ones. You can cut the inside and install a divider plate. It fools carb to act like a smaller carb for low end. Then you oval bore the top of carb for more volume after your slide gets past the divider plate. You pick up some top end like you do going with bigger carb. So you can make a 38 carb act like a 36 on bottom end and a 39 or 40 on top end. But I have never tried it on the VM's. I use to also, fool around with the tapers on the needles. You can machine the tapers to custom tune your throttle. On the newer Tmxx carbs, I cut my own needles. Sometimes you can lay your needle on a copy machine and make a copy of it. The copier will sometimes show the taper, especially ones with radical change. So if your bike has a hit to it when the taper hits. Sometimes you can put your needle in a drill press and move that taper further, allowing more gradual hit. You do this with a fine fingernail emery board.I use these lil sanding foam strips I buy from kraft stores.Then polish the needle. Reeds can be messed with as well. Sometimes lil more initial tension on them gives you more hit on bottom but you sacrifice some top end. But that is a good thing if your racing a Harescramble.

Attached is pic of a needle I changed. Mikuni uses minutes on there tapers. But once you understand the tapers you can sand them to change you throttle response. Usually a step taper makes a hit versus slow gradual ones. And if you thin a needle down, sometimes you have to change slide to add more air to fuel.

 

[justintendo]

luv the pipe & the jug porting. It leaves the port & heads vertical before heading sideways. It looks like it might be fatter & longer initially than my uptite pipe. For more bottom torque maybe?

would you mind posting some pics of your uptite pipe? these will be available again!!

 

[oldbikedude]

Ok, here is my uptite pipe on my 430.

 

[oldbikedude]

here's more

 

[justintendo]

thank you! looks like its a bit larger in diameter and shaped a lil different. that makes sense as george said they produce power everywhere, similiar to the stock pipe, just enhanced a bit. i like pipes!