LCGB Forums

Hi All,
what would cause a newly built ts1 to produce only 16bhp on a dyno.

spec as follows

60x110 crank
avanti piston
bgm ts1 cylinder head
vape variable timing ignition set
30 mm dellorto
taffspeed mk4 copy
casa close ration 4 speed box
19x46 sprockets
TIA

That is low Simon, who's dyno? How does it ride? It's not always about the figures, it how it produces the power on the road! I have a Muggy 225 lined and tuned by DSC Scotty with reed valve, only 18bhp on Chis' dyno but rides a dream. No powerbands, just torquey right through.

I'm assuming the dyno checked the carb and timing was ok ?

What packers have you used for the cylinder to compensate for the crank (how did alter the ports) ?

Stuck piston rings caused mine to lose 10hp (gummed up using too much oil when running-in)

Rich Oswald wrote:That is low Simon, who's dyno? How does it ride? It's not always about the figures, it how it produces the power on the road! I have a Muggy 225 lined and tuned by DSC Scotty with reed valve, only 18bhp on Chis' dyno but rides a dream. No powerbands, just torquey right through.

pulled 80mph on dyno going to ride it tomorrow but it was terrible before very boggy and wouldn't pull more than 60mph on the road.
will let you know tomorrow.

MickYork wrote:I'm assuming the dyno checked the carb and timing was ok ?

What packers have you used for the cylinder to compensate for the crank (how did alter the ports) ?

Stuck piston rings caused mine to lose 10hp (gummed up using too much oil when running-in)

hi mick yes jetting was rich and and timing was spot on.
packer used was a 3mm which put the piston level with exhaust port and the piston about 1mm below transfers

What about the all important squish measurement?

Simon_T wrote:

Rich Oswald wrote:That is low Simon, who's dyno? How does it ride? It's not always about the figures, it how it produces the power on the road! I have a Muggy 225 lined and tuned by DSC Scotty with reed valve, only 18bhp on Chis' dyno but rides a dream. No powerbands, just torquey right through.

pulled 80mph on dyno going to ride it tomorrow but it was terrible before very boggy and wouldn't pull more than 60mph on the road.
will let you know tomorrow.

If it pulled 80mph on a dyno then you will only get 60-65 on the road. Did you just put it on a dyno to see what it does or did you get the engine dialled in?

to get it dialled in,
got home and it wouldn't start again, changed stator changed coil pack and nothing.
however tried again today and I think ive had an earthing problem so will take it back to be checked on the dyno to see if my assumption was right

Hi there just reading through your spec, with regards to the transfer port openings/durations I suspect that they are to long, the 60mm stroke will naturally increase them if you do not actually lower the cylinder. Contrary to popular belief running a 60mm stroke actually requires lowering of the cylinder. If the port timings are not being measured the general rule of thumb would be to align the piston crown with the lower entry wall of the port.
I suspect it's making power to high up the rev range making the delivery of power difficult to find.
Also with regards to the Taffspeed copy, they are actually nothing like them and in no way mimic them on terms of performance.
Regards Scotty DSC

Also when you say timing was spot on, did you mark it up yourself? Or use the sip dial/ Mark's? And what are your firing points at, 200, 4000, 6000 + rpm?

dscscotty wrote:Hi there just reading through your spec, with regards to the transfer port openings/durations I suspect that they are to long, the 60mm stroke will naturally increase them if you do not actually lower the cylinder. Contrary to popular belief running a 60mm stroke actually requires lowering of the cylinder. If the port timings are not being measured the general rule of thumb would be to align the piston crown with the lower entry wall of the port.
I suspect it's making power to high up the rev range making the delivery of power difficult to find.
Also with regards to the Taffspeed copy, they are actually nothing like them and in no way mimic them on terms of performance.
Regards Scotty DSC

just a quick question to you mr scotty if I may as I know you know your stuff where as I am very amateurish.

if I bring the transfers in line with the piston crown will it make much difference if the piston crown is above the bottom of the exhaust port by a few mm ?

cheers.

ill check timings at the rpm soon

With regards the piston not being in line with exhaust port, this will have no affect, just keep an eye on the top ring as it's not ideal if it doesn't re-set itself into the the bore, by lowering the cylinder you will reduce the port timings, which will have a great affect on ride ability.

Because they actually only produce 16 to 20 bhp.
Forget all the b@@@@@@t that people brag about.

ROClarke wrote:Because they actually only produce 16 to 20 bhp.
Forget all the b@@@@@@t that people brag about.

im not about the Bragg I just thought it was 20bhp out the box without any tuning, however im aware its all about what gearbox what exhaust ect,
to be honest when I rode it I was impressed with the pulling power and it pulled 70mph on the road probably would go a little more so I was happy with that the dyno go did predict that and as long as its a little rich and safe is all that matters after seizing on the way to Poland a few year back.
thanks for all your answers though guys.