maximum size for bridgeless exhaust port

[dannygraves]

alright here are some crummy pics
first one of her complete with shiney new plastics, bars and bead blasted frame. thanks Justin and Mike for the bead blast and bars!


upsidedown exhaust



check out the boost ports



check out this upper boost port, I changed the angle, you can see by how the light is coming back up



exhaust before I was finished and before the exhaust bridge was releived. but it was at desired height of 190* (between 3-4mm)



hi-tech degree wheel



shot of markings before I added the port to the piston, check out my drilled boost ports and my opened up lower boost ports

[britincali]

I had to go check the shed to make sure my bike was till there ya copycat




Porting looks like its gonna rip man

[dannygraves]

hehe, ya, I wanted to do black sides and red fenders, but they don't sell the front and rear fender in the same shade of red like the fornt was flash red and the rear '01 red... retarded! so I went all black!

forgot to mention also the new to me silencer... thanks haulin arse, it was an '89-'90 and thats why it looks a little sideways, I thought the mounting was the only difference, but the bend is actually different, of well, it works.

thank, ya, she ripped real good on the street by my house, reminded me more of riding my friends R1 than how it was before.

[dannygraves]

right now its only running a regular FMF gnarly which really doens't go with the power I want, but my dewayne modded pipe didn't fit, so I beat it with the rubber mallet and heated it, then I ended up taco-ing the bend, so I threw it across my driveway while dialing dewayne... he said put it in a box and mail it, he'll fix it.

[dannygraves]

oh, also forgot Bobs kicker... thanks Bob, she starts a lot easier with the right kicker!

[AlisoBob]

oh, also forgot Bobs kicker... thanks Bob, she starts a lot easier with the right kicker!

[Roostius_Maximus]

I've seen the window of the pin boss be the limiter on how wide the port can go

[dannygraves]

I guess I found the one advantage to the un-machined wiseco.

[Roostius_Maximus]

ya, I was expecting to slap another engine together today, cuz i blew the center gasket out of my '88 yesterday.
The only jug i've got here is the bridgeless one that is still narrow enough to run the pro-x. I might just put the '88 cyl on the '86 bottom end and skip the piston break-in, gotta make the fordville hillclimb on sunday.

It started some serious trans oil smoking in the valley, and thanks to the irridium plug i rode it home 6 miles. She'd burnt 350ml out of the trans, well below the crank seal, so i'm eliminating as the problem.

[Roostius_Maximus]

anyone here runing a bridgeless jug that would like to share their ring end gap opinion?
I've got mine together, not fired it yet, and I've got that knot in my guts if i've got enough.

Danny, did you do any wet testing to see what affect those 2 new ports do for blowing the fuel directly out the pipe? sounds like it is making more power, but did you start small and work up to the size your at?

[dannygraves]

ya, this whole porting job has gone in stages. the additional ports were like my 3rd time pulling the jug off for more porting. When I first drilled them I made sure they were blowing the same direction and effectively adding charge to the exhaust side, but only in a way to direct a denser charge to the rear transfers. I didn't really look to see how the pistons position would effect them
now that I reshaped them both to make them match, they seem to work out a little better. We'll see how she rides on sunday

[Roostius_Maximus]

you're using a 85-88 style jug with the large reed area, I looked at drilling the same style ports in mine, but witht he old jugs I cant get the port high engouh because of the lack of material, in the newer jug i could deffinately get it where i want it.

I'm getting mine ready for the hillclimb saturday. Its also an '86 engine, but an '84 trans with a 92 clutch assy and cover.
I ride some trails, but usually just to a hill.
I cut the bridge out, left it narrow, and did some port work, put a reed on the factory cage thats for low end power.
Old fmf pipe and stock style almost-gutted silencer, not much option for this old 88 frame, and i'd like to get out of it before buying more specific crap.
I've got a head from a 90 with the bigger chamber, but the piston is proud of the cyl .003".
I'm still goofed on this ring end gap deal, the spec is the same from the a/c to l/c engines, but I dont want to screw it up. I'm using a pro-x in this engine.

[Roostius_Maximus]

ok, I read my last post, the piston was not .003" proud it was .039" (above the deck). This was as high as i could get the deck, i had to use a Honda gasket i had in inventory since 86 that was .045 compressed compared to the cometic (wiseco) version thats only .012". This thick gasket got the piston flush with the bottom of the ports at bdc (which would likely be a bennifit to go below the port and draw for a few more crank degrees, but i needed the room at the top of the block). The headgasket is the .012" cometic, that has the piston standing .027" into a dome thats tighter .035" than a stock 89+ head chamber. I am only going to run this thin gasket for c-12 fuel, and will change it to the stock .045" thick for trail riding.

what I'm getting at here is that theres alot to be said about the gasket and even the stock jug year to year. The '88 jug on this case would have taken the thin cometic gasket to make the port floor match the piston, and likely would have had the piston closer to the deck. The cyl measures the same in length, actually they're within .0015" of eachother and the '91 jug i'd spec'd.

Overall the engine made a hell of a difference to the way the bike works, its the horniest 500 I've got, ready to rip some shit right out of the hole. Its got the stock cage with a carbon-tech reed, FMF pipe ('88 style), and a stock silencer thats been opened. Quicker ( motor power and accelleration), smoother (power delivery is hard, but no other bike i have is as smooth feeling in the chassis as this), and higher revs than the '88 (that came out of the bike), the '91 bike, and the '00.

[Roostius_Maximus]

the bridgeless beauty

I did more work in the ports after this, but didnt take any pictures

[dannygraves]

nice

[blownbillybob]

it sounds like the bottom of your cyl. was cut .039 at one time or another,was that with no gasket ,but you measured the overall length and were within .015 of each other (cyl-cyl) the 88 cyl need the .012 thick gasket to match the ports and the later needed the thicker. so do you think the 88 ports are lower then the 89 and newer cyls. ?

[Roostius_Maximus]

I think the 86 ports are lower than the newer. the overall length was within .0015 thats 1.5 thousandths, the later cyl works better with the thin gasket. this was checked on the same block and same rod same piston within 5 minutes.

[blownbillybob]

.0015 my bad!!!!!!!!!!!!!!!!!!!!!!!!!!

[dubious01]

back to top, good info here