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Re: Cam timing question with A65 750 [Re: Mark Parker] #750010 09/21/18 1:53 pm
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Mark Parker Offline OP
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Static. The needle jets are Q2 which are about the middle range, and the different needles are mostly the same dia on the initial section, we have the leanest needles but there are numerous leaner needle jets, I will take a guess at size and order some. It definitely does this in relation to throttle position. The plugs come out with a layer of soot. It doesn't improve when running out of fuel.

The 883 is basically the same motor with more capacity, it doesn't get this sort of fuel stand off, but I guess that's expected. Have you seen this before Tom? I've not seen reversion doing this in a way that a light throttle cannot get past. Whipping the throttle open kills it dead. There are a few bits dangling off that need fixing so we can ride it, I cannot imagine that being a great experience at the moment.


mark
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Re: Cam timing question with A65 750 [Re: Mark Parker] #750081 09/22/18 1:16 am
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Mark Parker Offline OP
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Tested it up the driveway. It drives great on that little bit of useable throttle so it has to be just extreme richness on the needle jet.


mark
Re: Cam timing question with A65 750 [Re: Mark Parker] #750126 09/22/18 8:00 pm
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You know how J. Healy goes on about the needle jets with Amals and how you should check the actual size? You might check yours to see if they are to spec for a Q-2 and then go from there. Your symptoms are not subtle so the change will have to be more than a couple of numbers. I have had to adjust Mikuni's to specific applications so this is not a shocking situation.
Here's my story. A number of years ago I was working to 'fine tune' the DelOrto carb on my GS. I thought it was just a touch lean so I drilled out the needle jet just a wee bit. The symptoms were identical to yours. Nice idle but a wet fog when just opening. I was able to order a couple of new ones which fixed 'er up. They are measured in small increments of .001 in.
According to my Sudco book Q-2 should be 2.710. Maybe a P-6? That's just a SWAG. Cheers, PRT

Re: Cam timing question with A65 750 [Re: Mark Parker] #750128 09/22/18 8:49 pm
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If you have wild cam profiles could you be experiencing a phenomena common in piston ported two strokes "triple loading"
In two strokes , air is drawn into the engine picking up fuel, the piston descends and the air is pushed back up the port picking up more fuel and finally when the piston ascends again the air is drawn back into the engine picking up yet more fuel. This can be seen as a haze of fuel around the carb inlet.
When the engine comes onto the pipe the inertia of the air assisted by the exhaust keeps everything flowing in one direction.
Could you be getting the opposite effect?


BSA B31 500 "Stargazer"
Greeves 200 "Blue Meanie"
Greeves 350
Greeves 360
Suzuki GSX1100 EFE "Sorcerers Apprentice"
GM500 sprint/LSR bike "Deofol"
Jawa 500 "Llareggub"
Aprilia RSV Mille "Lo Stregone"
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Re: Cam timing question with A65 750 [Re: Mark Parker] #750129 09/22/18 9:01 pm
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BTW I am experiencing a similar problem on my B31 (Goldie motor) at 5000RPM.
My cams are std DBD34 clubman timed at standard 100/102.5, I am not getting any "stand off", occasional spit back (usually indicates weak?) but black plugs (rich?)


BSA B31 500 "Stargazer"
Greeves 200 "Blue Meanie"
Greeves 350
Greeves 360
Suzuki GSX1100 EFE "Sorcerers Apprentice"
GM500 sprint/LSR bike "Deofol"
Jawa 500 "Llareggub"
Aprilia RSV Mille "Lo Stregone"
'35 & '36 OK Supreme
Kawasaki ZZR1400 "Kuro no senshi"
Re: Cam timing question with A65 750 [Re: Mark Parker] #750164 09/23/18 11:51 am
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Many call it reversion, it's common on highly tuned two valve engines...Mufflers/megaphones can make it worse as will longer intake manifolds....What Tom says about fiddling with metering rods can help...If the bike doesn't have a crossover pipe between the exhaust pipes ,it may help,or it may need the crossover closer to the head..


79 T140D, 96 900M Ducati ,2001 Sportster....On a bike you can out run the demons..
Re: Cam timing question with A65 750 [Re: Mark Parker] #750172 09/23/18 1:47 pm
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Mark Parker Offline OP
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I'm pretty sure its simply way rich on the needle jets as Tom suggests. It's actually like our ride on mower with the choke on, as my wife pointed out.
It runs perfectly on the idle circuit and just above, it's only when the needle and it's jet become involved it plays up. It could probably cruise on 60-70mph if you stayed off the needle jet. It pulls great up the drive. So we will order some smaller ones tomorrow and find out. Just hope it hasn't put carbon on the intake valves, anything on them messes up flow, easy to lose 10-20cfm. Subaru have a potion to spray into intake manifolds to clean carbon off. The 883 runs very clean in the intakes, so when set up right hopefully this one will as well. It might be something you LSRacers could check for with big cams though. It may not build up on the valves running flat out so much but putting around it can.


mark
Re: Cam timing question with A65 750 [Re: Mark Parker] #750174 09/23/18 2:28 pm
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The valves stay clean as new on my LSR bike...Proper guide clearance and guide seals also helps keep carbon forming oil off the valves.And not much run time as you say..I believe Subaru and BMW cars have had issues with deposits on the intakes from oil getting oil in the combustion chamber.Generally on engines with carbs or port injection the detergents in fuel that washes the valves keep them clean from fuel deposits. I just had the carb and intake off my 97 Suzuki Quadrunner that sees a lot of time at low speed and idle...The back of the intake valve looked clean as could be...same for when I pulled the intake off a 03 Chevy V8 truck engine, intake valves were clean but there was some thin smooth black deposits on some parts of the intake port, perhaps due to the flow of gases..


79 T140D, 96 900M Ducati ,2001 Sportster....On a bike you can out run the demons..
Re: Cam timing question with A65 750 [Re: Mark Parker] #750188 09/23/18 4:44 pm
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i have a T120 750 with 34mm VM roundslidez.

it takes either a 159-P4 or 159-P6, with a 6DH2 or 6DH3 needle. the lean needle goes with the rich jet or the rich needle goes with the lean jet, eitber will work.

dunno about 38mm. but a 159-Q2 was way rich for my 750.

the VM and TM carbs use different components in some places. i'm not sure about tbe needle jets or needles.


every day you do not take a chance is a day of your life that you will never get back.
Re: Cam timing question with A65 750 [Re: Mark Parker] #750213 09/23/18 9:27 pm
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Mark Parker Offline OP
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With the TM they list only 4 needles 3 are 2.522mm before the taper 1 is 2.515mm, we have a couple with 2.522. They list 21 needle jets, 389 series, it will not even run at all on Q2, it stalls the motor. Tom recommends P6 which is 3 sizes smaller.

What I'm really curious about with this engine is if it will put out more power than the Rocket three and T150 750 F1 bikes that were so successful. It feels smoother than a three up to 3000rpm, it will be interesting to see how smooth it is through the rest of the range.

Last edited by Mark Parker; 09/23/18 9:29 pm.

mark
Re: Cam timing question with A65 750 [Re: Mark Parker] #750236 09/24/18 12:07 am
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Originally Posted by Mark Parker

[Linked Image]




mark, my system is so slow that i've only had images as of today.

what is the chassis, please? i like it a lot.

why is there a zip tie on the footpeg?

what is the width and diameter of the wheels?


every day you do not take a chance is a day of your life that you will never get back.
Re: Cam timing question with A65 750 [Re: Allan Gill] #750245 09/24/18 1:32 am
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Hey Allan, are you coming to the BSA rally over here? I'm not going, but a few guys are going from Sydney down the coast past here on their way, staying near here at Bega I think, and we are going to try to catch up with them. Why we want this 750 going and registered. The coast road north of here is brilliant for bikes. We also have room to accommodate people. Google Tathra NSW and you will see where we are.


mark
Re: Cam timing question with A65 750 [Re: kevin roberts] #750280 09/24/18 11:25 am
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Kevin it's an RGV250 chassis, from a road legal production racer sold in the UK Canada and Australia and other places, but I do not think the US. The little 250s were very fast with impressive lap times on Australian circuits, very peaky for a road bike, but guys riding them with scratches on their knee sliders were likely to embarrass riders of the bigger sports bikes. This is a '91 model. They had around 60-70hp at the crank. Wheels are 17" rear is 4.5" so can run a 160 tyre, front runs 120. I have Dunlop multi-compound sports tyres the thing is light and fairly easy on tyres. The 160 is actually at least 170 wide, they are for production racing and they fudge a bit in actual width.


The zip tie on the peg is for the kick start swing, though on this one it isn't really needed, on my red one it would hit. The kickstart pedal is new and a little different.


I do not know if Triumph motors will fit. The BSA is a tight fit and mounts at the back with two new plates which work out good. I'm confident we can get around 80hp or more at the wheel from this 750, the head is probably the best compromise between port size and flow, its around 10cfm better than the new Triumph 8 valvers. And one side of it I don't think I even went through anywhere. They go through into the pushrod tunnel which is easily fixed, but nicer not to go through. What ever power we can get we know this strong little frame is going to handle it. My main frame is earlier than this one and not quite as good. This is the model to have.


mark
Re: Cam timing question with A65 750 [Re: Mark Parker] #750281 09/24/18 11:51 am
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i thought it was another of those.

as you say, they are very rare in america, and when i find one for sale, very expensive. im still thinking about the 250 ninjas for a triumph motor, but havent got around to actuly measuring. too many other projects first.


every day you do not take a chance is a day of your life that you will never get back.
Re: Cam timing question with A65 750 [Re: Mark Parker] #750282 09/24/18 12:02 pm
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Originally Posted by Mark Parker
Hey Allan, are you coming to the BSA rally over here? I'm not going, but a few guys are going from Sydney down the coast past here on their way, staying near here at Bega I think, and we are going to try to catch up with them. Why we want this 750 going and registered. The coast road north of here is brilliant for bikes. We also have room to accommodate people. Google Tathra NSW and you will see where we are.



Hi Mark, I am yes, I was originally hoping to bring the bike but the price for shipping becasue crazy expensive. Shane has been really kind and offered me the use of his B44. If you manage to get over to Hall's Gap it would be really great to catch up... Lots of friends on this site who you get close to but still far enough away to be able to meet up. My friend and I are heading to the Yarra Valley also.... might be pursuaded to travel a bit further west


beerchug
Re: Cam timing question with A65 750 [Re: Mark Parker] #750632 09/26/18 11:10 pm
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Mark Parker Offline OP
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Kevin, I've seen a Triumph twin in an early Kawasaki ER-5 or 6 frame, a Japanese Rob North pretty much. Twin shock. I think it used the original Kawasaki tank, it looked really nice. Probably 2002 sort of vintage, I imagine they would be fairly plentiful and cheap.


mark
Re: Cam timing question with A65 750 [Re: Mark Parker] #750650 09/27/18 12:36 am
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[Linked Image]

that's a possibility. there's a couple of ER-6s around for sale, no ER-5s. but this area is full of the little ninjas. clearly i need to spend some time with a tape measure.

i'll have to source another motor. the extra one i have now is going into into a period track bike this winter.


every day you do not take a chance is a day of your life that you will never get back.
Re: Cam timing question with A65 750 [Re: Mark Parker] #750852 09/28/18 9:18 pm
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Stein Roger Online Content
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I saw a Triumph T140 engine in the same type Suzuki frame as Mark’s on the Isle of Man maybe 20 years or so ago.
It was featured in a bike magazine later, but I couldn’t say how the engine was mounted. I’ll look for the magazine l when I get home. As I recall it was a standard engine, nothing fancy.

Re: Cam timing question with A65 750 [Re: Mark Parker] #751586 10/05/18 7:13 am
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Mark Parker Offline OP
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This is a video of what the BSA does. Still waiting on leaner needle jets, hopefully that's all it is.

https://www.youtube.com/watch?v=F6hos12a3lE&feature=youtu.be


mark
Re: Cam timing question with A65 750 [Re: Mark Parker] #751918 10/08/18 10:43 am
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Mark Parker Offline OP
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Fitted leaner needle jets but its more or less the same though with much less fuel stand off. CDI units are here so might set them up and see if it's the same. And after that try my carbs.


mark
Re: Cam timing question with A65 750 [Re: Mark Parker] #752031 10/09/18 7:47 am
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Well there you go. Two DC CDIs, two coils, two pulse coils, big fat sparks and it's alive, once we put the richer Needle-jets back in. Timing light works at all revs and we can probably open the plug gaps a little. If we added wiring plugs and terminals the total cost of the ignition was less than $100. Advance looks good. It will just be a matter of seeing how it is on the road. Sounds crisp and good.


These are tiny little coils, is there a down side to using this type of set up?

Last edited by Mark Parker; 10/09/18 8:01 am.

mark
Re: Cam timing question with A65 750 [Re: Mark Parker] #752035 10/09/18 8:30 am
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This is the type of coil and DC CDI. What it looks like, may not be the exact same one.

[Linked Image]


We have instruments, headlights and blinkers and taillight to wire in, and some paintwork to do. Ben likes the idea of blue and white, and it would look good, even if not exactly BSA colours.

[Linked Image]

Very happy the thing is now revving up and down as it should. And so glad I didn't mess with the cam timing trying to get it running right. I wonder what I had wrong with the Honda ignition? Wonder if the 883 would start and run better with this type of ignition? Would running a bigger plug gap give more hp I wonder?


The ignition on the 883 does not have enough energy to fire the timing light very well at higher rpm, the CDI does.


Last edited by Mark Parker; 10/09/18 8:34 am.

mark
Re: Cam timing question with A65 750 [Re: Mark Parker] #752156 10/10/18 6:55 am
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Hi Mark

Good to hear you got to the bottom of the issue. Where does that ignition unit come from!

regards

John

Re: Cam timing question with A65 750 [Re: Mark Parker] #752165 10/10/18 1:06 pm
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Mark Parker Offline OP
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The units are like this, possibly a different brand, I'll find out, but it would be good to see how they work. Ben ordered the wiring plugs to go with them and we found a wiring diagram. It has a bit of a miss after mounting them properly, so I'll check and solder the connections. Crimp terminals on light wire isn't great. Actually I'll replace the light wire going part way to the triggers. Even on a 360degree twin two of these may be good, where you place the triggers on the points plate determines the firing angles. They need to think they are crankshaft triggered so two screws sitting up on where the old auto adv sat are needed otherwise it won't advance when required.

https://www.aliexpress.com/item/Hig...vid=63f8f085-6c35-41a9-8274-191b1007cf62


mark
Re: Cam timing question with A65 750 [Re: Mark Parker] #752279 10/11/18 7:19 am
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Hi Mark

Thanks for the information.

regards

John

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