Bonneville America Forums Forums Technical Forums Performance Mods before/after bigbore and headwork photos

here's the head, before:



After, with bigger valves:



Intake runner before:



After port/polish:



Here's the jugs bored out with the Wiseco Jugs pressed in:





I'm going to send the head off to another machine shop to have Speed Triple valve springs cut in. This will allow a higher redline and prevent valve float at high rpm from the bigger valves that are 2 grams heavier than stock.

The motor should be back together in about 2-3 weeks. Dammit.

Looks good. Can't wait for your first ride report. How much material did you remove from intake passage?

looks like they didn't remove much. I just told them a mild port/polish. I didn't want hogged out heads, just smoother.

Thanks for the pics Jeff. There's been a a few bikes with carbon buildup on the valves(see here). Did your stock valves look anything close to the ones in the link above?

Those new valves look like they sit a lot higher. Is the piston to valve clearance adequate? Do you have to compensate at all if they are? For example, maybe a thicker head gasket?

Good luck with the rest of the build.

cant wait to see dyno numbers

Frank

It's looking good man.wondering how you are determing your total compression? Your doing a nice job especially not butchering the head up...got a feeling it's going to run!
take care,
Kenny

SWEET!!! Remember to break that bad boy in using regular, NON-synthetic oil !!!! Can't wait to see the dyno results. Did you dyno before the mods?

Purdy

Forgot to ask, why have someone else do your springs? Just buy a $30 tool, compress them down, remove collets and springs, replace springs, reinstall collets, uncompress, rinse and repeat.

Pat, I'm having speed triple inner springs mounted, so there will be an inner and outer (Stock) spring. The head has to be cut with a special tool (that had to be made specifically for this, hence the other machinist) to allow fitting of the inner valve springs. This will help with the big valves to prevent valve float. They weight 2g more than stock. Also, should I ever buy/order a high RPM cam I should be able to rev safely to 10,000 rpms (along with a new rev limiter).

I did not dyno before hand, shame on me, but I figure most bonnies with exhaust and the airbox elim make around 55-60ish hp, and that's being fairly optimistic. I'm going to break the motor in (using conventional oil of course) then do a dyno run and make sure it's tuned right to figure out how much power it's making. Realistically I'm hoping for 75-80hp, with stock carbs. Then I'll get some mikunis, probably 36mm TMs, and get it tuned and do another dyno run, hopefully making 80-85hp but dammit 90rwhp would be nice!

Would this motor be a candidate for the one tooth exhaust cam move?

An 865 is not.

Hey Derek

Quote:

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There's been a a few bikes with carbon buildup on the valves ...

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When I had the ST in for the last recall, the #1 honcho in the workshop was telling me about carbon build-up reported on the ST engines and suggested some sorta additive they sell for it.
A small bottle added after a near-full tank fill up helps he says.
Fill the tank to near full then shove this stuff in and hey presto, everything gets a coating and all is good in the world.

Yeah I've been doing that every 5,000 miles for the last couple of years. Haven't been using any specific brand of additive, just whatever catches my eye on the store shelves. One bottle is usually good for 20 gallons of gas, so I just dump a little in for 5 or 6 tankfuls. But without pulling the head, I have no idea what kind of carbon buildup I might have.

Ah yes, the old acetone in the fuel myth. Check these out:

Re-visiting the Acetone in Gasoline concept

Thoughts on the effects of acetone in your fuel system

As far as spraying water into the carb (nebulized = atomized), have you ever seen what a few drops of water in a carb can do (btw, it gets atomized before entering the combustion chamber).

I'll stick to carb cleaner solutions.

I know there's some persons not in accord with the acetone theory...

I've used and also some people I know used it for long time with no problems. I've noticed the engine run smoother, better acceleration and better fuel mileage, both my Harley and the Kawa ZRX1200.
I didn't stop using, but sometimes I forget to use because makes me sick to have alway a small plastic bottle with acetone to add into the tank after every gas filling.

But I've found some people (expecially mechanics) use it for two different purposes:

1) clean the combustion chamber from carbons. Using acetone for some months.
2) reduce unburned HC in exhaust gases for a short period, just a pollution control and car revision.

In my country after the first 4 years of life (and every 2 years after the first control) a new car need a control to see efficiency of brakes, lights and exhaust emissions.

Using acetone you can drop from 10 up to 50% unburned Hydrocarbons and pass a pollution test.
It appens with ethyl alcol mixing.

The mixing is done only for a short time, just the pollution control.

About water, on Harleys and open airbox like Big Sucker, it appens during bike washing or driving under the rain that the filter become wet and some drops of water get sucked into the engine.
Nothing appens if only few drops of water get sucked.

But talking to some mechanics about this question, the olders of them told me about this trick, spry water into the carb was used for internal combustion chamber cleaning and other defects diagnosis.
Older techniques, now misused, but still known into that old techie not-written literature...

I have used water down the carb for years. It cures "dieseling" problems due to a piece of carbon glowing and causing run-on (running after the ignition is turned off). I have done this many times with cars but have never used a spray bottle, just a cup with the engine running at around 3500 rpm. You have to be careful not to pour too much in because of the chance of hydraulic locking the engine (you have been warned). In a motorcycle with side drafts, a squirt bottle would work fine.
Another piece of "old tech". If you need to find a stubborn exhaust leak, get the engine up to operating temperature and pour a little brake fluid down the carb. It will smoke like crazy and you can see the leak. It is also a pretty good prank. Beware though, it smells pretty bad.

Dan

As I was reading down I was about to mention the water trick but I see Mechano beat me to it. Be very sparing in the amount though remember cold on hot = bad. This is not just a Harley trick I have been doing that on small block Chevys for as long as I can remember to clean em up before checking valve clearances. Naturally clean em today adjust em tomorrow.