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Post a pic if you would. Bolt up the boot to the head and look into the opening. If there is a lip on the head showing scribe it with a scribe or other pointed tool and then just blend it in to about an inch in or less. If you open it up too much it will slow down the velocity of the intake charge. That's why the good carb boots will usually be tapered to speed the intake charge and why cheap pods rob you of power because they are usually restrictive compared to the stock boot and seldom have the taper.
I just realized my 400 has the carbs off so I went and looked and fingerfucked the boot. As expected I doubt you will find the port to be smaller than the boot. While I can see a very slight lip on one edge I believe if you manipulate the boot as you tighten it down you can center it without the need of any port matching.
Port matching intakes is the very minimum you should do on intake side
Personally I would do a bit of clean up and re-shape.
Marc has it right about loosening screws and centering best you can before doing any cutting.
I check manifold boots on carbs as well, you generally find they need opening up slightly (don't mess with the carbs though)
Exhaust side needs opening up to gasket size for top half of port taper down so bottom has a definite step.
You can work it out from valve head size, 80% on a 7 degree taper from as close as you can guess center of valve to get length to pipe. (or you can do a bunch of trig/math with angles and things)
I do things as simple as possible,
eg valve head 20mm, 80%=16mm.
Port length 50mm
Draw parallel lines then 'open up' at about 7 degree angle both sides (or 3~5 degree for a 'long' port, about 8x diameter)
measure distance at the 50mm end of drawn lines to get diameter
It's actually much much quicker to do than try to explain
I read at http://www.mototuneusa.com/power_news_--_homework.htm it was 70% , but as I haven't started my bike I and don't build engines fora living I can't confirm. Others at his site seem to agree and I also read similar stories on thumper talk. I must warn you he does go on a bit so the pages are longer than they need to be.
I did follow his breakin theory with my 450 mx bike and all 5 pistons I replaced looked nice and clean and the bore looked good.
The full listing of his pages is avail at http://www.mototuneusa.com/thanx.htm
It's been so quiet on the bike front unfortunately
I've been away for work, plus I'm still waiting on the motor to come back from vapour blasting. I did however buy a SS bolt set in preparation for when I button it back up:
Only need to find a bucket of cash so I can order bearings, gaskets, oil seal kit and cam chain tensioner blade, then I will be in a position to button the motor back up.
Work and family have to take precedence, (without cash you can't do much of anything, and without some support from 'better half' it would end up sold as part finished project ;D )
At least everything is still moving along 8)
Went to see my buddy Darren from DNA Custom Cycles yesterday to order up some billet goodness. He's a whizz kid on the CNC mill and I've got him to work up some magic pieces and replace some of the bits I made myself so that I can get the fit/finish where I want it to be. Bits to be made are:
1. Front Engine Mounts
2. Rear Engine Mounts (I need some help on this one)
3. Turn signal bolts (will explain later)
4. Updated ignition button mount (to bring the gauge closer in to the triple clamps)
5. Front fender brackets (replacing the crap, thin Alu ones I made)
6. Custom caliper carriers (replacing the existing carriers and the mounts I made)
He's making quite a name for himself locally with his SRX350 which recently won the Deus Bike Buildoff in Sydney:
So on to the rear mount question. I am replacing the flimsy Alu mounts I originally made, easy for the front as I copied the mount and measured it up, however I didn't do this on the rear. Does anyone have dimensions for the rear mount so that I can recreate it? I would need hole spacing and also the offset between the frame and engine mounts.
So on to the rear mount question. I am replacing the flimsy Alu mounts I originally made, easy for the front as I copied the mount and measured it up, however I didn't do this on the rear. Does anyone have dimensions for the rear mount so that I can recreate it? I would need hole spacing and also the offset between the frame and engine mounts.
I've measured the offset from the back of the engine side, to the front of the frame side. Your bracket may be thicker? The bit at the rear is part of the battery mounting, so not sure if you'll need that??
I do, but I thought you may already have those. The engine bolt hole is 12mm (for the 10mm bolt), and the two frame bolt holes are 10mm, but have an M8 captive nut behind them. Not sure if you're going to thread your new brackets or just nut and bolt them?
Have you heard from your vapour blaster?? Can't wait to see how those parts turned out ;-)
Small update. I had an email from the blasting chap [Dave Mac in Sydney], the first run through the vapour blaster has been completed and he is doing a bead recharge so he can run it through again and get a smooth flat finish.
Had the option of shiny finish, but chose to go flat Alu.
Will be ready to pick up tonight, but unfortunately I am busy with work for the next couple of days so probably won't get the chance to grab the motor until Friday.
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