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Tuning a 2001 790cc Triumph Bonneville


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I've been asked by a friend of a friend to make his Hinckley Bonneville quicker and faster. It goes ok at higher revs, but very little at bottom end and midrange. Don't know the revs, as there is no tacho. Not sure what the top speed should be, but as there's not much accel at bottom end, I've just reduced the front sprocket from 17 to 16 teeth. It revs a lot easier and pulls like a train up to 100mph(on the track). Still don't know what the top speed is though. Gonna leave the gearing as is for now and have a look at the valve clearances and valve timing to see if it's anywhere near what it should be. My friend is thinking of a 904cc Wiseco big bore kit with 10.25:1 compression ratio, OR a lot of cylinder head work, including a gas flow, but not different cams or valves. The cost is slightly more for the head work. I know what my inclination is. What do you guys/girls think?

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Get a cheap digital tacho that clips onto an HT lead so you can get an idea for the rev range.

If its not revving out in top gear you can drop the gearing further.

Bigbore kit would be my choice. Quick, easy and less things to go wrong!

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Yeah,thanks guys, I think we might start with the big bore kit. The exhausts are non standard Triumph cans, that are a bit less restrictive but not loud. Strangely they are stamped" Not for road use", fitted by a Triumph dealer and not picked up on the last MOT ??? Valve clearances will be the first job, but a few O rings and gaskets will need replacing for checks and then shims need ordering and fitting with cams out. Just need my mate to leave it with me for a week, as he's going to Brightona on Sunday. When we take the head off to fit the big bore kit, I will strip and clean it and do the valve guide checks, fit new seals and have the valves refaced and seats recut for max compression. The gas flow job will have to wait for a cash injection, but to be honest, as it's been priced at around £1000 ( shock, horror ), I think we will see what performance is like before committing to it. My mate wants to change the carbs for Dellortos or ,god forbid, Amals, so I think a carb expert will be needed for rejetting etc, after airbox mods. Phew!!!

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if he is going for big bore and gas flowing then surely he will want bigger valves to help it breath and longer duration cams with slightly more and longer lift on them,and coping with the extra i would go stainless one piece valves and phosphorus bronze valve guides made to suit the valves and inserted into the head

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Ah sorry mate. Sense of humour failure there. If you ever want any help with the bike, that you can't cope with, just ask or bring it to mine . You never know , you might learn something.

Yes Alan, a top end blitz is planned, but he's pleading poverty at the moment, so best VFM would be the big bore kit. I am going to check valve clearances next week and if I can get hold of a suitable degree wheel, I will check and adjust the valve timing to optimum.

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Ah sorry mate. Sense of humour failure there. If you ever want any help with the bike, that you can't cope with, just ask or bring it to mine . You never know , you might learn something.

Yes Alan, a top end blitz is planned, but he's pleading poverty at the moment, so best VFM would be the big bore kit. I am going to check valve clearances next week and if I can get hold of a suitable degree wheel, I will check and adjust the valve timing to optimum.

alan who the fook is alan u is alan i is not alan and just to confuse it even more he isnt alan either :cheers:

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Have a look on the RAT forum Alan.......someone is bound to have done some of this work on their Bonnie...... :wink:

Saw something a while back where a guy had done stuff to his Bonnie and got it up to 97bhp......I'll see if I can find it again...... 8-)

Gotta agree that the big bore kit is the more cost effective way to start.....and will help the bottom end.......gas flowing will only really help at the top end..... :wink:

Red line on the Bonnie is 8.5K rpm mate.......and I think the top speed is around 110-115mph.... :wink:

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Thanks Bob. Was browsing the RAT forum and saw your name. Just waiting for acceptance email. That article would be useful. Have heard claims of 80bhp , but 97 is awesome, if true.

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Can't find the 97bhp article Alan......but did stumble across links to this guy......http://www.bobfarnhamtuning.com/bonneville.asp

There's the Hyde Harrier.....which puts out 80+bhp at the rear wheel..... 8-)

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Thanks for that Bob. I have eMailed Bob Farnham, T3 Tuning(next door to BF) and Norman Hyde. Not even an acknowledgement after 3 days? Bobs price of around £1000 for the full job, 904 kit and headwork, is half what my mate was quoted by Bob ? Gonna stick with the big bore kit, probably via Norman Hyde for time being, at least until my mate gets another slug of cash.

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Just buy a sports bike its easier.

I don't see why anyone would bother with trying to tune up something like a bonnie when it will still be a bonnie when its done. Just buy a faster bike for the money you will need to spend on this one to get less speed. Any 2nd hand Jap sports bike should be faster and more fun. Plus you wont have the insurance issues if it goes tits up.

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Just buy a sports bike its easier.

I don't see why anyone would bother with trying to tune up something like a bonnie when it will still be a bonnie when its done. Just buy a faster bike for the money you will need to spend on this one to get less speed. Any 2nd hand Jap sports bike should be faster and more fun. Plus you wont have the insurance issues if it goes tits up.

 

For the same reason you dont buy a proper off roader... Any modern enduro bike would be far more capable off road than the machines you take offroad... but wheres the fun in that?

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You really don't get it do you mate.

 

I do "get" it but just don't see the point when there are far better bikes to go fast on. If its for a class in some competition then fair enough. But if its for the road then why bother. I see lots of "slammed" cars with big bore pipes and all the cool gear going down the motorway as I blast past them in my standard rep mobile with a boot full of tools and spares. There they are having their fillings knocked out by the lack of suspension and the stupid idea that fitting wide wheels and then fitting narrower tyres on to miss the body work but at least they think they look "cool".


Even if you speed the bonnie up it will still be a bonnie. But it doesn't end there does it the handling mods come next followed by the better brakes. So once you start adding all this lot it it makes no sense. Just keep the bonnie for cruising and buy a cheap sports bike ( or even a standard Jap bike like a bandit ) for the speed.

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No , I was right the first time. You don't get it. If you can't make a meaningful contribution to the thread, then keep your opinions to yourself.

 


Steady on Alan!! you asked for peoples opinions and this is what he has done gave his opinion!!!


anyway back on topic


If it was me personally I would be buying another bike to go fast on! but thats me! I was toying with the idea of a big bore kit in the TL about a year ago but for the cost (best part of 3k) I could have sold mine and bought an R1 or blade! but where is the fun in that!


What is he using the bike for? if its just road riding then depending on the budget I would be looking at sorting all the suspension out first and make it handle then some advanced riding lessons.... at the end of the day its the corners that slow you down and if you can keep the speed up around them then a decently ridden bike will keep at a fast speed


if he wants to get there faster then again depending on the budget I would be looking at big bore kit lightened and balanced crank some fast road cams all dialed in any head work is just really to get the last few bhp out of it and wont be worth it unless its racing


I would also be adjusting the gearing to match too

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Having ridden Mandy's Bonnie a fair few times I'd say that the handling and brakes are ok......but it could do with a few more horses..... :wink: The 902cc kit is not going to make it into a Gixxer killer, but will give the bike a bit more grunt.....which the brakes and suspension should be well capable of handling..... 8-)


Why do it?.......obviously plenty of people are keen to do this as there's several big bore kits around.....and if you like a particular bike, but feel it could do with a bit more oomph....then why not? Mandy often gets people round her bike at meets discussing it and asking questions.......yet to see groups of people standing round a Bandit showing the same sort of interest...... :wink:


His money.....his choice......end of...... :wink:

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It's the main thing that Bonnie fans would like to see coming out of Hinckley - a powered up Bonnie twin. Personally I think they'd be better off bringing out another retro triple (not cruiser style) like the discontinued Thunderbird Sport maybe tuned up a bit from the 80odd bhp - 1050 triple???????


Handling on the Bonnie is fine, twin brakes on the front would be good but the brakes work fine.


Top end acceleration is pretty good but, as you've noticed, it can be a bit slow of the mark. Top speed of 110 is realistic, a ton feels pretty fast and your wrist is pretty much nailed at that speed ( all on a private road).


It red lines at 7000, tacho only goes up to 8000 and it pulls really well from about 4000 without dropping a gear


I like having a tacho - your mate might consider getting the double clocks. They look better too IMO.

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