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#891116 09/19/22 9:47 am
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I built a 750 Trackmaster A65 for a client 2 years ago, From day one it has been a bugger to start reliably, i have gone through everything but to no avail,
iv'e changed carbs, tried mikunis, pwk's, and its now on Wassel 30's premiers, 25 pilot, 3 slide, standard needle top groove, 2 types of ignition, different inlet tract length, tappet clearance etc, i know how to tune carbs from many years working on race bike, but this one gives me headaches, it currently is running a Vape ignition plus battery and is timed correctly with a good spark, i use 99 octane super unleaded from Esso as it is the only fuel i can find that is ethanol free, One of the only ways i can get it to start is to hold the throttle wide open, which seems to work on most occasions now, has anyone come across this before? Once started it runs very well on the track, On the Dyno it made just under 50 bhp at the rear wheel and 44ftlbs of torque.

277525044_5436582306361481_8764287207574454282_n.jpg
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PEH #891139 09/19/22 2:04 pm
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Nice looking machine!

I'm not familiar with the Wassel Vape EI but assuming the battery is charged and passes a load test thats probably not the issue. Do you have a higher lift cam and high compression pistons installed? My 750cc A65 race bike can be a bear to start sometimes due to the 14:1 compression and trying to kick start on the wrong side of the stroke. How is the fuel flow into the carbs? The engine appears to be rotated a bit forward increasing the angle of the carbs which may be giving some issue on the starting procedure? Does removing the air filter setup ease the starting? Also, have you made sure the A/F ports in the carbs are fully cleaned, alot of times when I find hard starting issues on a Concentric carb its from the A/F ports being clogged up.

Hope you get it figured out as the bike looks like its a blast to ride.


1955 BSA Bantam D1 Plunger
1956 BSA A10RR Street and LSR Bike
1961 BSA C15S
1966 BSA Lightning
1966 BSA Spitfire - Soon to be an A50 Powered LSR Bike
1969 Triumph T100C
1970 Triumph TR6R
1970 Triumph TR6C
1972 BSA Lightning LSR Bike
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PEH #891142 09/19/22 2:29 pm
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My Wassell/Vape ignition requires the twin cylinder engine to be kicked through two compressions with one long hard kick, to start.

It doesn’t spark on the first signal from the trigger.


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I doubt it's the ignition, A65's like a drop of squirt to fire up, with amals a press of
the tickler always helps. Try a couple of priming kicks with no ignition and either
wide throttle and choke on or well flooded. Then get past tdc and give it a boot with
the throttle just cracked.
You may find the needle needs to come up one notch these days.

That's a lovely job BTW.

NickL #891203 09/20/22 12:35 am
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my 650 triumph was an easy starter, even with high compression, long cams, and large carburetters. but space considerations made me switch to an electric start. that may solve your problems easier than anythjing else.




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Thanks for the reply, Its running 9-1 pistons, the battery is new and good, the cam is a hepolite / wassel copy of the standard lighting cam, its made by Newmans who make a similar one for SRM, iv'e gone through every thing on it several times but i cannot find anything untoward, What do you mean by A/F ports?

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Nick, You are describing more or less the method i use. i checked the compression a few hours ago and it ain't great. around a 100 psi, with only a hundred miles or so on the bores and pistons, iv'e heard that the JCC pistons do not come with good rings, so that area needs looking into, iv'e been playing with twins for a long time and can normally find a fault when there is one but this one is starting to get at me.

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Kevin, This was my suggestion to the owner but he is adamant he wants it as it is, so i have to continue looking for the answer to the problem.

PEH #891219 09/20/22 6:49 am
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Those pistons are more likely GPM than JCC.
Their rings aren't the best but i used them loads of times with no problem.
I would have expected compression to be a little higher than that so it maybe
worth riding the thing for longer and checking when it's done a few miles.

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You are correct Nick, I'd forgot that i fitted the B44 pistons, running in race bikes is not easy around here, so i usually just gun them from the off, iv'e got away with it so far, Ed at EV engineering mentioned i should check my cam timing as that may be causing low compression? as i mentioned the bike goes very well once started, 50hp is not to shabby for a mildly tuned bike, 44ftlbs of torque is not bad either,

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PEH #891230 09/20/22 11:59 am
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Originally Posted by PEH
I built a 750 Trackmaster A65 for a client 2 years ago, From day one it has been a bugger to start reliably, i have gone through everything but to no avail,
iv'e changed carbs, tried mikunis, pwk's, and its now on Wassel 30's premiers, 25 pilot, 3 slide, standard needle top groove, 2 types of ignition, different inlet tract length, tappet clearance etc, i know how to tune carbs from many years working on race bike, but this one gives me headaches, it currently is running a Vape ignition plus battery and is timed correctly with a good spark, i use 99 octane super unleaded from Esso as it is the only fuel i can find that is ethanol free, One of the only ways i can get it to start is to hold the throttle wide open, which seems to work on most occasions now, has anyone come across this before? Once started it runs very well on the track, On the Dyno it made just under 50 bhp at the rear wheel and 44ftlbs of torque.


Hi Paul,

I could be way off here, but I usually find starting with throttle wide open is needed if the cylinder is flooded with fuel (or rather more than it would like to start the bike), often this happens if the carb has been flooded when it didn't need it or maybe its had a few too many unsuccesful attemts at starting. Opening the throttle full will put less suck on the pilot circuit and allow more air to pass the main throat of the carburettor. I've started many a B50 this way...

Im not familiar with the QC of the Wassel premiers, but the AMAL ones tend to be about spot on regarding float height. It would be worth checking your float height and see what your getting....

just looking at your photo again (beautiful bike!) the rear of the bike looks higher than standard... might be affecting the float height on all the carbs you have fitted????

Just a thought...


Now let’s all have a beer beerchug

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71’ A65 823 Thunderbolt (now rebuilt)
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PEH #891237 09/20/22 2:01 pm
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Originally Posted by PEH
Thanks for the reply, Its running 9-1 pistons, the battery is new and good, the cam is a hepolite / wassel copy of the standard lighting cam, its made by Newmans who make a similar one for SRM, iv'e gone through every thing on it several times but i cannot find anything untoward, What do you mean by A/F ports?
I was referring to the passages in the carb body behind the air mixture screw on the side of the carb, if these get clogged up starting can be a PITA. I am also thinking Allan is on to something with the flooding and needing to have the throttle wide open for starting. The carb angle could be allowing improper seating of the float needle dumping too much fuel into the cylinders.


1955 BSA Bantam D1 Plunger
1956 BSA A10RR Street and LSR Bike
1961 BSA C15S
1966 BSA Lightning
1966 BSA Spitfire - Soon to be an A50 Powered LSR Bike
1969 Triumph T100C
1970 Triumph TR6R
1970 Triumph TR6C
1972 BSA Lightning LSR Bike
1974 Triumph T150V
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Originally Posted by Blown Income
The carb angle could be allowing improper seating of the float needle dumping too much fuel into the cylinders.
I was thinking that but didnt want to run the risk of sounding any dumber than I already am laugh
Makes me feel much happier about it knowing that someone with a bit more knowlege has said it smile


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68’ A65 Lightning “clubman”
71’ A65 823 Thunderbolt (now rebuilt)
67’ D10 sportsman (undergoing restoration)
68’ D14 trials (undergoing transformation)

PEH #891256 09/20/22 4:28 pm
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I have found that bikes with a leaking head gasket, often need full throttle to start. The fact that your compression is low with high compression pistons installed, makes me wonder if this is a possibility.

Ed from NJ

PEH #891280 09/20/22 8:51 pm
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I always reckon that 100 psig on a compression test is the "rocking point".
Below 100 and you probably wont get it to start.
Above 100 and it should start.
So IME you are right on the balance point.
I would look at getting higher cylinder pressures.
Just my two cents worth of course.

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Allan, the bike is a good inch off the ground on the stand, it does give a higher looking stance, the float heights i will check again, but i have tried several heights so far,

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Blown income, The Premier type carbs are new, they have been gone through several times and done about a 100 miles, it ticks over nicely once warmed up, which would indicate the pilot circuit to be ok? I will be looking at the float height again, but it has been changed a few times already, The rear height is exaggerated by the stand i believe, the standard A65 port does have a slight angle to it .

PEH #891462 09/22/22 7:42 am
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Off the stand and with seat rails parallel to the floor we only have the standard inlet port angle. I use a 5 degree swing arm angle for my flattrackers.

20220330_143734.jpg
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I take your point Ed, but if you felt the performance of this bike under you i think you would discount a blown head gasket.

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Tridentman, i will be looking closely at the compression over the winter off season, It has been mentioned to me by a well known A65 tuner that the cam timing could be affecting the compression, i did it off the rocker arms originally, i will be checking again from the pushrods.

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PEH #891475 09/22/22 10:24 am
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i have long cam timing in my race bike, some 296 degrees. the last time i measured, i get 140 psi with my foot with around 11.75 to 1


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PEH #891479 09/22/22 11:06 am
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I have a feeling you're going to be taking the head off and having a look....................
Maybe he's over-buzzed it and kissed the inlets a fraction. (Red mist syndrome)

kevin #891481 09/22/22 11:26 am
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Kevin. That is the sort of psi i was hoping for, I will be going in over the winter.

NickL #891482 09/22/22 11:28 am
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NickL, Yes, Im gonna have to go in and go through it see what i can find.

PEH #891551 09/23/22 8:47 am
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bit late to the party, your tune is not far off my own bike, it should start easily, your compression is very low , start there. last time I checked my bike was around 180 psi. I have had cams with the wrong marks before, always check with a degree wheel.

My starting regime, from stone cold. fuel on, choke on, select 2nd, paddle down hill, ignition on, bump at 10 mph, starts in 2 yards.
With no hill.Choke on ,tickle one carb, kick to prime, ignition on, kick , vroom.
Rest of the time ,if sitting more than 10 mins, choke on, start , choke off immediately.

Ignition, Boyer, 6V coils, NGK B8 plugs, AMAL concs 30mm ( clean pilots with #78 drill).

There cant be too much wrong with the dyno numbers you are getting.
As Allan says, wide open throttle to start suggests flooding, overtickling maybe?


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