Bonneville America Forums Forums Technical Forums Performance Mods grinding the heads?

this winter im thinkging of beefy up my 02 bonny america. not sure whether ill go 865 or big bore 905. but a friend suggested grinding the heads a 10 thousandth instead. mhe said it should give more horse less heat and would only need a slight valve adjustment meaning less cost at the same time.. thats question one.. question 2 would it then also be effective to the power to grind and one of the other mods, has anyone done that, problems with it, advice would be wonderful. ive never modded a bike before. today was the first by removing that god awful cali bs. i pulled the cans and exccess vaccuum lines and capped the nipples. that even seemed to give more power back and now it stopped bogging and stalling.

Pistons you know will work with no fuss. Taking meat off the head leaves valve and piston crown clearance questions and will that tube allow the head to seat and not leak. Will the timing chain tensioner take up the slack? (probably but still a consideration) You will probably have to egg the bolt holes in the head steadies too.

thanks, yeah i know changing most anything from stock is a can of worms. thats why ive never done more than plugs and higher grade oem's. but i feel like i need more than 790cc. but like the bikea and its classic look.ive also been looking for a 6 speed tranny to both get more speed and better fuel economy at higher speeds. she screams at 85mph. is it neccessary to go that fast not necessarily, but most people i ride with have 1100cc and larger bikes. so keeping up in the pack at times can be difficult any idea on where to find a 6 speed for the 02 bonny?

What sprockets are you using? My basically stock Speedy, keeps up abreast with my partners six speed 110 CVO Harley, no matter how fast he goes. P!sses him right off too. I do not believe there are any 6 speed tranny options for the modern Triumph line at the moment, so all you have is sprocket options.

not sure, im new to the world of brit bikes. only owned hondas and kawais
before. all stock. so far as i know. i bought her used from a dealer...
thre triumph was off brand to them.. it was traded in to them for a ctx.
but i fell in love with her look the moment i saw her. ive been dealing
with some bog out lately and am figuring its due to some dirt and debris in
the carbs, gotta save the money for the the mech on that. not a carb guy
but know that they are slightly out of sync and poorly tuned. i get some
pretty gnarly blueing on my pipes and usually the right pipe more so and
sooner than the left, tomorrow im changing the plugs and giving her an oil
change hopefully the 18 mm thin wall will work. most of my questions are
pipe dreams, but help me align towards setting an attainable goal to soup
up and tune this bike to be worthy of the name bonneville

Sounds like you're possibly running lean, deal with that soon. Burnt valves do not need to happen. With synced and properly jetted carbs, adjusted valves and the right sprocket ratio for your riding style, you may not need all these costly upgrades. 790 s have a hot cam to begin with, but a 904 kit with 10.5 to 1 pistons and you will definitely be able to go faster.

I easily run over 100mph and I run the 16/42 sprocket combination on a mostly stock 790 that I tweeked to where it is now. I had a friend with a modified night train and it pissed him off that I could slowly pull away from him.

thanks im changing the plugs tonight to ngk iridium whats the proper gap for those. after that im gonna drain the bowls. i think i have a litttle debris in the carbs.i ran some seafoam thru her and now im getting some intermittent bog down and power loss. i also just found out i should have been running 89 or higher octane. found a station with 91 ethanol free and that seemed to help a alot. even the blueing seems to be less on the pipes with the higher octane fuel.

no clue to my sprockets. i only bought this bike the bieginning of july. just getting to know her. thats why so many questions on ways to get more smooth power and dial her in to be the bike she was meant to be.

Pull the front cover and count the teeth, we can assume (always dangerous) your rear is a stock 42T. If you want more get up and go off the line, install a 16T, a less buzzy (lower RPM) top end, a 18-19T. When I ran stock diameter rear tires, I preferred a 17T, the best compromise to me. It takes a 36 mm socket and a long breaker bar to do the changeout and a helper to stand on the rear brake really helps. I have a 3/4 and 1" dr socket collection, so I have it easier than some. It's a 10-15 minute job with all the tools in hand. Worry about tuning issues, then sprockets if I was you.

yeah my concern right now is tuning. the sprocket ratio seems fine. im not the biggest motorhead, more of a shade tree. when its running lean its getting too much air, correct? if thats the case how could i go about reducing the air? in an easy cheap manner. i plan on bringing it to the shop when the season ends here in upstate ny to get the carbs cleaned, tuned and synced. and possibly the exhaust, id like a little more rumble and growl from her. i just believe loud pipes save lives. cant see me?, youll damn well hear me.

You can enrichen the fuel mix by going up a bump with your pilot and main jets, for mid throttle, you add a shim washer to your carb needle. Our carbs are tuned by throttle position,. not RPM and the start of the process is installing the correct main jet for your intake and exhaust at wide open throttle. The more air in and exhaust out, the bigger the main jet. Google and BA.Com is your friend, but you have to do some info search for yourself.
jet_calc

I would say first step on an older bike running lean is to make sure you do not have any vacuum leaks then on to filtration, pipes, and jetting.

as far as i can tell there arent any vaccuum issues anymore since i pulled the cali evap (leaks or vapor locking) i havent tried to change the inline filter at the t fitting for the carb because i dont quite unterstand where and what needs to happen for that. nervous about getting over my head, when i asked the mech he looked at me like i had 2 heads, i assume its a stock cvk carb so the jets should be normal, but have heard that the early bonnies were design to slioghtly run lean. would plugging the a snorkel and dialing up the fuel mix screw do the jon without causing detremental damage. or atleasat run her better till the end of the sean when i can oput more time into the carbs/intake myself. and to the pipes is there an easy way to open them up i.e. remove some baffle? i come here to search for info because i have a difficult tim finding iunfo elsewhere. wrong model year info pops up a lot.

No, plugging the snorkel would be a bad idea. Only way to dial in the carbs is to get them jetted right and adjust the mixture screw correctly. The inline fuel filter is easy to find. Trace the fuel line from the tank to where it plugs onto a T fitting between the carbs, the filter in in that T fitting where the main line plugs on. I have never had to mess with mine on my 04.

ok thank you, after i changed the oil today i did some more snooping. i found that the right side carb boot (between carb and engine) is in need of replacement. i already ordered a new one, until then i took off the hose clamps and wrapped it in electrical tape to smooth out the ride until it comes in. and wow what a difference. i still think shes a bit lean but ill get that taken care of at the end of the season. and look into possibly jetting and putting a pipes with a bit more growl on her. thanks for all the advice. youve made figuring out this bike a lot less frustrating.

Spray carb cleaner around the intake rubbers and squirrel condoms, the idle will change if you have a vacuum leak, be careful not to spray painted surfaces.