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650 for the track #671286
10/17/16 11:29 am
10/17/16 11:29 am
Joined: Jan 2006
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Asheville, NC
Mike Baker Offline OP
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Got my feet wet racing this season, and will say I've been bitten by the bug. The Aermacchi ran well, I placed pretty good and will be back next year. I've decided to run a second class, Classic 60's 650, and will be building a Triumph over the cold months. I've picked up a solid 71 T120 bottom end to use in a 69 chassis. I like the 71/72's for the heavy flywheels, stronger rods, metric bearings and beefy gearboxes. I have a Rob Hall prepped head already and will use a T140 intake cam. The motor will ideally pull well from 4.5k to 6.5k, maybe 7000 on occasion. I'd like to bump compression over stock a bit maybe to 10ish to 1. Any suggestions where to source pistons? Also, any thoughts for an exhaust system? Rules spec a 2 low pipe system.
Would big TT pipes fit the bill or would something a little smaller diameter work better? Using 32mm Mic's, so experimenting with extending inlet tracts would be easy.
I know there is no 1 size fits all here, but appreciate opinions.
Thanks, Mike

Re: 650 for the track [Re: Mike Baker] #671294
10/17/16 11:59 am
10/17/16 11:59 am
Joined: Oct 2012
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Running from demons in WNY
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MAP forged tight quench 10.5 pistons, only slightly heavier than stock cast... I've used a few sets. None better in my opinion, the lower wider dome doesn't mask combustion and I believe they are made by Ross..Most of us LSR racers use 1-1/2 pipes...


650 Triumph modified production LSR record holder 133.1 MPH... Twin 650 engine Triumph LSR that goes sorta fast...
Re: 650 for the track [Re: Hillbilly bike] #671351
10/17/16 6:38 pm
10/17/16 6:38 pm
Joined: Dec 2013
Posts: 3,528
ohio, usa
kevin roberts Online content

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i'm running 11.75:1 JE pistons, but i'm not fast yet. the dome is really, really, high.


237 grams, i think they were.


live every day.
die only once.
Re: 650 for the track [Re: Mike Baker] #671394
10/18/16 4:54 am
10/18/16 4:54 am
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Rotherham - S. Yorkshire
Allan Gill Online happy
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Kevin, have you tried advancing/retarding the ignition timing yet? It will take more time for the flame to travel across a domed piston than a flatter crown.


beerchug
Re: 650 for the track [Re: Mike Baker] #671404
10/18/16 8:13 am
10/18/16 8:13 am
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Dallas Texas
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I would try and find a 1963 to 1965 frame to use or at least the front section of frame. The steeper steering head angle will make it turn better. Longer shocks in the rear also.

Re: 650 for the track [Re: Allan Gill] #671417
10/18/16 9:52 am
10/18/16 9:52 am
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Running from demons in WNY
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Originally Posted By Allan Gill
Kevin, have you tried advancing/retarding the ignition timing yet? It will take more time for the flame to travel across a domed piston than a flatter crown.


I believe Kevin is using a dual plug head so flame travel is less of an issue....
There's many opinions on high domes and flame travel...


650 Triumph modified production LSR record holder 133.1 MPH... Twin 650 engine Triumph LSR that goes sorta fast...
Re: 650 for the track [Re: Mike Baker] #671502
10/18/16 9:43 pm
10/18/16 9:43 pm
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Posts: 1,866
Asheville, NC
Mike Baker Offline OP
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I've heard that about frames. I have a 69 frame though at this point. Longer shocks, yes. Been thinking about using a 71/2 front end, boring the top clamp, sliding the forks up some and somehow clamping them there.
Recent dyno experience with my street 650 and another 650 similarly built - same compression, both 32mm carbs, same cams timed very close to one another. Mine made about 38 peak hp, the other made 45. mine had a long flat torque curve, the other was quite peaky. Neither of us push the motors past 6500 RPM. The only difference that we could come up with was the pipes. Mine is an old MAC 2-1, 1 3/8 dia. with a short Cone muffler and the other is a homemade stepped affair, rather short and large diameter. What we really need to do is to swap the ex. systems and see what happens. I'm sure there is a compromise there somewhere.
With a 4 speed, that wide torque band would be great for pulling out of corners. On the other hand, my bike could get run over on a long straight if I don't find some more top end.
First Race next year is the end of Feb.....

Re: 650 for the track [Re: Mike Baker] #671656
10/20/16 9:49 am
10/20/16 9:49 am
Joined: Aug 2006
Posts: 429
Dallas Texas
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Mac exhaust system and pipes are junk. Throw it in the trash. 1 5/8 pipes if possible.

Are limited to a 4 speed gearbox? Spend the money and put a 5 speed in if rules allow. This would be the best upgrade you could do. Down shifting a 4 speed Triumph vs down shifting a 5 speed Triumph into a turn is night and day different. It is much easier to be smooth on the track with a 5 speed gearbox. Smooth equals faster lap times.
You could fit T140 triple clamps and still use the 71/72 fork legs. Just slip the forks up past the taper. If using a conical hub front brake you can install a T140 disc axle in the front wheel to fit forks. You will also have to put longer stud and spacer where the wheel bolts to the fork lower.

Re: 650 for the track [Re: Allan Gill] #671803
10/21/16 5:23 pm
10/21/16 5:23 pm
Joined: Dec 2013
Posts: 3,528
ohio, usa
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ohio, usa
Originally Posted By Allan Gill
Kevin, have you tried advancing/retarding the ignition timing yet? It will take more time for the flame to travel across a domed piston than a flatter crown.

allan, i'm still running a stock 38 BTDC on it, because all my time was spent in trying to get other things to fit and/or work right. i'm anticipatng working with the timing this winter.
Originally Posted By Hillbilly bike

I believe Kevin is using a dual plug head so flame travel is less of an issue....
There's many opinions on high domes and flame travel...


not yet, tony-- the current head is one plug per cylinder, which is why i haven't messed with the timing.

on my twin-plugged street bike, it's fastest with the spark retarded 8 degrees, to 30 BTDC. at 28, it's slower. more than 38, and it pings.

i plan to twin-plug the next head because i want to run much closer to the edge than i am with this one. the domes are way up there:





live every day.
die only once.
Re: 650 for the track [Re: Mike Baker] #671819
10/21/16 8:43 pm
10/21/16 8:43 pm
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Originally Posted By Mike Baker
. . . Neither of us push the motors past 6500 RPM . . . .


i can run 7300 top end in third on my 650, and i've seen 8000 several times (lol, by mistake). but that was LSR.

where is your horsepower peak? can you short the gearing and get that higher rpm anywhere on the course?


live every day.
die only once.
Re: 650 for the track [Re: Mike Baker] #680881
01/11/17 8:11 am
01/11/17 8:11 am
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Posts: 1,866
Asheville, NC
Mike Baker Offline OP
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Starting to come together, may be able to start it this weekend. Wound up with a 750 intake cam, question about what to shoot for RE: valve/ rocker clearance. Stock 650 is .002" if I recall, and a 750 is somewhat larger I think. With R tappets on a 750 cam, where should I be?
Thanks, Mike

Re: 650 for the track [Re: Mike Baker] #680883
01/11/17 9:54 am
01/11/17 9:54 am
Joined: Oct 2012
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Running from demons in WNY
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I think around .008 is ok.... The late Pete R used to recommend about 100 degrees on the intake lobe centers...If you're going to be running the engine in the 5000-7000 rpm range ,102 or so intake lobe center line might be ok and give more intake valve to piston clearance...


650 Triumph modified production LSR record holder 133.1 MPH... Twin 650 engine Triumph LSR that goes sorta fast...
Re: 650 for the track [Re: Mike Baker] #680927
01/11/17 3:03 pm
01/11/17 3:03 pm
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Rotherham - S. Yorkshire
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Around 102-to-103 is the magic number that magacycle (think Johnson too) and harmons and collins list for a lot of their cams

You can advance/retard the cam a couple of degrees to suit where you want peak power, I've found in one instance on the standard bsa cam, 4 degrees advanced gave a good power throughout, the head was worked to give good power to about 7200 and it gave those revs in second and third. (Never managed to get it into top to find actual top speed or if it could pull the same revs there too)

Last edited by Allan Gill; 01/11/17 3:12 pm.

beerchug
Re: 650 for the track [Re: Mike Baker] #680935
01/11/17 3:52 pm
01/11/17 3:52 pm
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Bolton Lancs UK
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Andy Higham Online content
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6500 RPM is wasting at least 1000 RPM on a race engine


1955 BSA B31 400cc "Stargazer"
1962 Greeves 200cc "Blue Meanie"
1962/67 Greeves 350cc
1967 Greeves 360cc Challenger
1984 Suzuki GSX1100 EFE "Sorcerers Apprentice"
GM500cc sprint/LSR bike "Deofol"
Jawa 500cc grasstrack
2003 Aprilia RSV Mille "Lo Stregone"
Re: 650 for the track [Re: Mike Baker] #680958
01/11/17 6:08 pm
01/11/17 6:08 pm
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Posts: 1,866
Asheville, NC
Mike Baker Offline OP
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Thanks, Tony
Wasn't sure if my *mix* of 650 and 750 intake parts would need some compromise valve lash.
As far as valve timing, I got to 102.5 intake and 103.5 exhaust lobe centers. And with the steel rods and nitrided crank, i feel pretty confident it can safely turn 7500 for more than a couple of races.
How's your project? I'm going to try to get to NY to visit my mom next month, may need to stop into your laboratory for an inspection?
Mike

Re: 650 for the track [Re: Mike Baker] #680969
01/11/17 8:14 pm
01/11/17 8:14 pm
Joined: Oct 2012
Posts: 3,261
Running from demons in WNY
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Originally Posted By Mike Baker
Thanks, Tony
Wasn't sure if my *mix* of 650 and 750 intake parts would need some compromise valve lash.
As far as valve timing, I got to 102.5 intake and 103.5 exhaust lobe centers. And with the steel rods and nitrided crank, i feel pretty confident it can safely turn 7500 for more than a couple of races.
How's your project? I'm going to try to get to NY to visit my mom next month, may need to stop into your laboratory for an inspection?
Mike


Mike, if you want the power more crowded around 7000 rpm, try 105 degrees intake centerline...
My projects are scattered...The double engine Triumph is over at my rider's place so he can fabricate a chain guard...The single engine 650 racer is here on the work table and the engine is sitting on bench for disassembly..I may or may not change cams...
You are more than welcome to stop by...it's not like I have a job and need to be somewhere... grin


650 Triumph modified production LSR record holder 133.1 MPH... Twin 650 engine Triumph LSR that goes sorta fast...
Re: 650 for the track [Re: Hillbilly bike] #681032
01/12/17 12:15 pm
01/12/17 12:15 pm
Joined: Oct 2012
Posts: 3,261
Running from demons in WNY
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Mike, I pulled the engine in my 650 LSR bike today for some potential cam changes....The current cam is a genuine Sifton 390..
Originally when assembled a few years ago I set the cam timing by Sifton intake and closing figures...
Today I checked the intake and exhaust lobe centers...102.5 intake ,107.5 exhaust....Sifton recommenced 105 on both...
I'm going to retime the intake and exhaust to 105 degrees looking for more top end power..

You have probably seen the dyno sheets on the engine, 55 rear wheel hp @ 7050 RPM and 46 ft pounds of torque @ 5200 rpm...At 7000 rpm there's still 41 ft lbs of torque...Power falls away rapidly after 7200 RPM...Also 10.5 compression, slightly raised intake port floors, 37 x 1.5 inch straight pipes and 34MM Mikuni flat slides...
Sifton 390 is a bit hotter than the 750 intake but you get the idea regarding cam timing...Plenty of power from 4000 rpm on up without needing to exceed 7000 rpm...


650 Triumph modified production LSR record holder 133.1 MPH... Twin 650 engine Triumph LSR that goes sorta fast...
Re: 650 for the track [Re: Mike Baker] #681107
01/12/17 11:06 pm
01/12/17 11:06 pm
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Asheville, NC
Mike Baker Offline OP
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I wound up using a set of MC pistons, not sure of C/R, Beno said probably around 10.5. Class rules call for pipes under footpegs and IME, after you raise the pegs, stock pipes are the next thing to touch pavement, hence I'm going with TT pipes and no silencers for now. Do some dyno and track time and see how things go. "Period" carburators, 32mm max. Had some Mics here so thats what's going on the other end.

Re: 650 for the track [Re: Mike Baker] #681162
01/13/17 10:00 am
01/13/17 10:00 am
Joined: Oct 2012
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Running from demons in WNY
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Yes, the Forged MC pistons seem to be 9.5 or 10.5 compression.Have to use period drum brakes?..You appear to be a decent rider so as long as the machine is reliable ,you will be competitive...


650 Triumph modified production LSR record holder 133.1 MPH... Twin 650 engine Triumph LSR that goes sorta fast...
Re: 650 for the track [Re: Mike Baker] #681175
01/13/17 11:23 am
01/13/17 11:23 am
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Bolton Lancs UK
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To ensure a reliable engine that is easy on the rider get the crank dynamically balanced. this ensures perfect balance both with the pistons and rods but also end to end balance


1955 BSA B31 400cc "Stargazer"
1962 Greeves 200cc "Blue Meanie"
1962/67 Greeves 350cc
1967 Greeves 360cc Challenger
1984 Suzuki GSX1100 EFE "Sorcerers Apprentice"
GM500cc sprint/LSR bike "Deofol"
Jawa 500cc grasstrack
2003 Aprilia RSV Mille "Lo Stregone"
Re: 650 for the track [Re: Mike Baker] #681240
01/14/17 12:26 am
01/14/17 12:26 am
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Asheville, NC
Mike Baker Offline OP
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Rules state drum brakes. Bike will have stock 69 running gear. For now. Appreciate your confidence in my abilities, Tony. I do try to be safe and competitive.
I spent some time weighing the reciprocating parts and comparing them to stock and surprisingly total weights of my parts were in the neighborhood of 20 grams per side heavier than an average of stock. MC pistons were quite a bit lighter than stock, rods were a bit heavier. Given what I found, I thought I'd try it without balancing. For now.
I don't expect to do this without some experimenting and learning as I go.

Re: 650 for the track [Re: Mike Baker] #681241
01/14/17 12:28 am
01/14/17 12:28 am
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Asheville, NC
Mike Baker Offline OP
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eBay pipes came today. Not TT's, regular outside frame pipes. Dam.

Re: 650 for the track [Re: Mike Baker] #681250
01/14/17 5:21 am
01/14/17 5:21 am
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Allan Gill Online happy
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If your. It going to balance, get some really accurate scales instead/as well, that way you can at least reduce rocking couple. By equalising Rod and piston weight. One of my conrods was 17g heavier than the other when my bike was stock, but the pistons were matched, it was smooth up to 4K revs then kicked in like a switch and fast cruising above 70 wasn't comfortable.

But for the price of balancing, I'd get it done.


beerchug
Re: 650 for the track [Re: Andy Higham] #681269
01/14/17 10:19 am
01/14/17 10:19 am
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Nova Scotia, Canada
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Originally Posted By Andy Higham
To ensure a reliable engine that is easy on the rider get the crank dynamically balanced. this ensures perfect balance both with the pistons and rods but also end to end balance


Whenever I read a statement like this, I have to ask what balance factor "ensures perfect balance"?

Singles and 360 twins suffer the same problem - - you can't balance out the vertical (inline with bore) reciprocating force without introducing a subsequent horizontal out-of-balance force.

To the best of my knowledge, BSA, Triumph, and others would have started with a 50% out of balance in both directions and then just kept making changes to get the most comfortable ride for normal speeds. Double that speed that we are doing in racing and everything changes. I've tried 60% and 65% balance factors and after a few days of WOT for 3 miles (Bonneville Salt Flats), I end up with blisters on my hands (literally!)

Can someone suggest in which direction the balance factor should proceed for our normal vertical motors for sustained high RPM?

Tom

Last edited by koncretekid; 01/14/17 10:22 am.

Life's uncertain - go fast now!
Re: 650 for the track [Re: koncretekid] #681495
01/15/17 9:11 pm
01/15/17 9:11 pm
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push it to at least 70 percent but i don't think i would go over 75 percent


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