Bonnie engine project

[Speed3Chris]

Cool. Not sure if the TPUSA HC pistons warrant premium fuel..at 10.8:1 CR. BB kit is 11.5:1 however so likely the case there.
Can't hear any cam noise in the sound track
Have fun.

 

[Gretsch]

That bike looks outstanding!

 

[Aussie_T100]

Cool. Not sure if the TPUSA HC pistons warrant premium fuel..at 10.8:1 CR.

I was sure that the TPUSA HC pistons were 11.2 to 1 - my mistake. Considering that Triumph recommend premium fuel even with the stock 9.2 to 1 comp, when pushing to 10.5 to 1 and above as well as throwing 3 degrees timing advance in to the mix one would think that premium fuel would be an absolute must. That's my opinion anyway.

 

[Aussie_T100]

That bike looks outstanding!

Thanks for the compliment. I think it looks outstanding too but then I'm slightly biased. :cheers:

 

[musicswapshoppe]

Looks shithouse mate

 

[Speed3Chris]

I was sure that the TPUSA HC pistons were 11.2 to 1 - my mistake. Considering that Triumph recommend premium fuel even with the stock 9.2 to 1 comp, when pushing to 10.5 to 1 and above as well as throwing 3 degrees timing advance in to the mix one would think that premium fuel would be an absolute must. That's my opinion anyway.

Most have success running reg fuel in with stock engine and timing advance. I run mid grade in mine. Increase compression and timing and things change of course. My plan Aussie...not sure when it will be...will be TPUSA HC pistons + head shim. I will clay the motor to determine optimum head shave which will likely be just under 1.0mm. AussieDave has Weisco pistons + 1.0mm head skim and he states his CR is 11.6:1 which should be about perfect...and close to TPUSA BB kit of 11.5:1. If going to the trouble of pulling the head and cams, my thinking is the compression needs to be in the 11.0-12:1 range which is almost standard fare these days for stock motors. My view anyway. Corresponding with the Germans, they have taught me these motors have way too much combustion clearance stock for efficient combustion...about 1.7mm. Optimimum squish is about .7mm +/- and best way to determine this is with claying the motor. Running a bit less compression as you do is an opportunity for a bit more timing advance so the end game likely isn't too much different. I think you have been been prudent with your mods. Reworking the head + BB kit + cams and going to new carbs or in my case throttle bodies gets real expensive fast and to me if spending $3-4K on the motor for 15 hp seems silly in totality...might as well just buy a Street triple like Gretsche did.

 

[sweatmachine]

Shaving the head is a bad idea

 

[Speed3Chris]

Shaving the head is a bad idea

Have you done it? Likely not.
Cam Timing diff? Almost imperceptible.
The Germans know more about hotrodding these bikes than anybody. Virtually all of them don't do BB, use stock pistons shave the head AND lose the bottom base gasket for more squish. They also run elaborate cam timing scenarios well outside the box by changing crank sprocket orientation.
There is no universal path to hp...Montuu, AussieDave, Sandro and countless others have shaved the head...even with added piston height of HC pistons...and I will be in line. If you talk to Thunderbike...they go a step further and say the only difference between their cams and running Weisco BB versus shaving the head is mid range ONLY...upper hp is almost identical...even with increasing displacement 39 cc's. This I believe is because unless the pump size (bore X stroke) is furnished with more air aka carb or TB upgrade in size, there isn't much hp benefit of slight increase in cc's. This is also true when going from 790 to 865 motor size which is a bigger percentage jump...many well tuned 790cc motors put out as much hp as milder cammed 865's...not as much torque however. Since Thunderbike doesn't sell HC pistons, they don't have a dog in the fight of whether skimming the head is problematic...it isn't for those that have done it. The added cc's of BB give the torque but the compression ratio be it skim or HC pistons with cam timing provide the hp. 1.0mm skim will bring the CR on a stock motor up a full pt to 10.2:1 and with base gasket removed about the same CR as HC pistons. As the afore mentioned guys, I like the idea of light head skim and keeping the base gasket + HC pistons and will follow that path.
PS: The other trick the German's play is they remove 1-2 plys off from the head gasket + head skim + base gasket removal. These motors stock have too much head to piston clearance for best combustion efficiency.

 

[Aussie_T100]

Looks shithouse mate

Well at least my shithouse runs :lol:

AU$ is up over US$0.90 I see, made any decisions yet?

 

[Aussie_T100]

Most have success running reg fuel in with stock engine and timing advance. I run mid grade in mine. Increase compression and timing and things change of course.

Easy to get confused when discussing fuels considering that our two countries use different ratings. Here in Australia we have three basic grades regular unleaded (91 RON), Premium unleaded (95 RON) and Ultra unleaded (98 RON). Premium unleaded (95 RON) is what Triumph recommends be used in the stock engine and I'm guessing this fuel is similar to your mid grade in the US.

I have used regular unleaded in my Bonnie with the stock engine when nothing else was available but I avoid using it if I can. I did notice on one occasion when running regular, riding two up and up a mountain range that the bike definitely did not like it at all but on most occasions when riding solo over flat country there seems to be no noticeable effects, at least when using "normal" throttle openings.

It may very well be that you can safely run premium unleaded with 11.5 to 1 comp and 3 degrees advance in these engines but I would be very concerned if I was forced to run regular unleaded in such an engine due to unavailability of premium fuel and that is a common situation in parts of this country. Even with 10.5 to 1 and 3 degrees advance I reckon I would be pushing the envelope by running regular unleaded especially if I happened to be loaded up on a trip or two up.

Having seen the damage caused by pinging, detonation, pre ignition - what ever you like to call it - I want to avoid the possibility at all costs.

 

[Speed3Chris]

Easy to get confused when discussing fuels considering that our two countries use different ratings. Here in Australia we have three basic grades regular unleaded (91 RON), Premium unleaded (95 RON) and Ultra unleaded (98 RON). Premium unleaded (95 RON) is what Triumph recommends be used in the stock engine and I'm guessing this fuel is similar to your mid grade in the US.

I have used regular unleaded in my Bonnie with the stock engine when nothing else was available but I avoid using it if I can. I did notice on one occasion when running regular, riding two up and up a mountain range that the bike definitely did not like it at all but on most occasions when riding solo over flat country there seems to be no noticeable effects, at least when using "normal" throttle openings.

It may very well be that you can safely run premium unleaded with 11.5 to 1 comp and 3 degrees advance in these engines but I would be very concerned if I was forced to run regular unleaded in such an engine due to unavailability of premium fuel and that is a common situation in parts of this country. Even with 10.5 to 1 and 3 degrees advance I reckon I would be pushing the envelope by running regular unleaded especially if I happened to be loaded up on a trip or two up.

Having seen the damage caused by pinging, detonation, pre ignition - what ever you like to call it - I want to avoid the possibility at all costs.

Agree. Both CR and ignition timing are game changers relative to fuel octane.
I wouldn't run 10.5:1 CR with 3 degree timing advanced on regular either. In fact, I wouldn't run regular with any increase in CR or timing advance. I run mid grade even on my stock motor for safety margin. Many factors contribute to predonation including AFR and you identified that load matters as well in combinatiion with the thinner mountain air.
Cheers.

 

[Phil-1100]

Excellent bike with good mods, well done mate

 

[Aussie_T100]

Excellent bike with good mods, well done mate

Thanks for the compliment it is much appreciated. :beer:

 

[Flaco]

Aussie_T100,
I'm curious about the "Bike Shed" video you posted on your Vimeo channel.
Fill us in, as inquiring minds would like to know who's and where?
Better not be all your bikes!http://vimeo.com/11760588
Thanks...
Flaco...

 

[Aussie_T100]

Aussie_T100,
I'm curious about the "Bike Shed" video you posted on your Vimeo channel.
Fill us in, as inquiring minds would like to know who's and where?
Better not be all your bikes!http://vimeo.com/11760588
Thanks...
Flaco...

Sadly only in my dreams is that my bike shed. The shed and, more importantly, its contents belong to a chap known as Sao who lives in a western Queensland town called Emerald. I had the privilege of staying overnight at Sao's place a few months back when on a ride with a group from the Local British Motorcycle Owners Association and a memorable stay it was too. The hospitality shown to us by Sao and his wife was truly outstanding and we had a really good night drinking and talking bikes into the wee hours of the morning. That stay was the highlight of the ride really but you can see the whole saga here:-

http://www.newbonnevilleriders.com/forum/showpost.php?p=87558&postcount=1

 

[Aussie_T100]

Thanks to the Aussie dollar hovering around parity with the US dollar I finally succumbed to temptation and purchased a set of Keihin FCR39's for my bike. I've had them for a while but only got around to fitting them this week due to some health issues, the holiday season & life just generally getting in the way.

Fitting these carbs was fairly straight forward with the exception of some clearance issues between the air filters and the side covers but that was easily resolved. Mind you having to disassemble half of my bike just to change the airbox was not much fun, that was more work than the carbies themselves.

Once fitted I was surprised by how easily the bike started and how well it ran with these carbs fitted straight out of the box, Carlos certainly hit a home run there. With the bike warmed up and the idle speed adjusted I did a quick check for fuel leaks etc and donned my gear. Once out on the road I was impressed with how sweet the bike was running, probably as well as it did with the CVK's that I had spent weeks tuning.

Performance wise I'd say the improvement is very similar to that gained from fitting the Thunderbike cams and Wiseco 10.5 to 1 pistons, if my seat of the pants dyno is to be believed. Of course I couldn't resist giving it a WOT test as soon as I found a suitable location:-

http://www.youtube.com/watch?v=qinwaie9yCI

I didn't get off entirely scott free though as I seem to have a minor intake leak which refuses to identify itself. I've tried the old spray all of the joints trick while the bike is running but could not detect anything by that method. I guess I'll be working on that problem over the weekend instead of riding the bike. :chin:

I made a video of my whistling Bonnie and uploaded it here:-

http://www.youtube.com/watch?v=MTjZRDmHhmU

The odd thing with this is that the bike does not display any symptoms of an intake leak other than the whistling noise which is a bit perplexing.

 

[mikenva]

Are you sure you have a air leak? Dont sound like it does,its breathing alot more air that might be what you are hearing.

 

[Pete R]

Yeah Oz, it might be the new induction noise you're hearing. Going from the airbox to pods does make the induction sound much more prominant.

If you were sucking air she'd be running like a busted bum. It seems pretty smooth on the video clip? One way to check would be to connect your vaccuum gauges up and see if one carb is out of kilter compared to the other - if one is sucking air and running lean then they will be out of wack. If they're both ok then either they're both leaking or it's a new sound you're hearing.

I think (and hope) she's just talking to you. Telling you how wonderful she feels

 

[Aussie_T100]

Are you sure you have a air leak? Dont sound like it does,its breathing alot more air that might be what you are hearing.

No I'm not dead sure I have an air leak but that is the most obvious answer to the whistling noise which only shows when manifold vacuum is high. On the road when the engine is under load the whistling noise is worse than it is in the static video above which is what worries me.

At steady cruising speeds the whistle is not evident but it can be induced by twisting the throttle a little and then it stops again as the engine reaches a speed that matches the throttle opening. It seems to be dependent on manifold vacuum more than air flow and that says air leak to me but I'd be happy to be proven wrong.

If that whistling noise is typical of FCR39's then I'd be happy to except that but all of my previous experience tells me there is a problem here. I'll be removing and refitting the manifolds today to recheck my work just for my peace of mind anyway. Damn good riding weather today too.

 

[Aussie_T100]

I think (and hope) she's just talking to you. Telling you how wonderful she feels

Oh yeah, she's talking to me alright, funny how these bikes seem to be happier when you give them a good flogging. If I just doodle around on her she gets all cranky after a while but give her a quick blast and she's suddenly happy again.