UKDRN

Do you own or know the whereabouts of a piece of UK Drag Racing History or just want info on a particular machine.

Moderators: timetravel, ukdrn

 #40175  by shasta
 
With the help of my niece a couple of weeks ago, we had another go at starting the bike with the new beefier starter handle fitted. Firstly we found fuel was not getting to the rear carbs so a new fuel tap bracket was made to get it lower than the tank outlet. Spinning it over we had a couple of coughs and flames from the front exhausts as the fuel ignited but no start,so the ignition timing needs to be gone over again from the start to check that it's set up correctly. We also noticed that the belt tensioner had bent the inner engine plate allowing the belt to become slack. A new arrangement with an outrigger support is now being made.......plenty of time on my hands to get round to do stuff like this. Unfortunately I don't think Dragstalgia will be taking place in July which has been the target we have been working towards. Hope everyone out there keeps well and see you at the strip when all this is over!!
 #40177  by shasta
 
Time spent around the shed the other day has seen the new primary belt tensioner nearly finished, just might put a couple of lightening holes in the plates.
Attachments
IMG_0021.JPG
IMG_0021.JPG (2.29 MiB) Viewed 19348 times
IMG_0020.JPG
IMG_0020.JPG (2.34 MiB) Viewed 19348 times
 #40184  by shasta
 
New primary belt tensioner finished and fitting. Did put in a couple of lightening holes... bound to make a lot of difference on this big lump!Photos show old set-up, lightened plates and the new unit in place. Now to check over that engine timing and ignition timing again, which will hopefully show up why it's not roaring into life! Keep safe.
Attachments
Old set-up
Old set-up
IMG_4077.JPG (1.73 MiB) Viewed 16371 times
Plates with lightening holes
Plates with lightening holes
IMG_0014.JPG (930.13 KiB) Viewed 16371 times
All fitted
All fitted
IMG_0026.JPG (1.93 MiB) Viewed 16371 times
New tensioner in place
New tensioner in place
IMG_0025.JPG (1.63 MiB) Viewed 16371 times
 #40188  by shasta
 
Latest work has been setting up the engines relative to each over to get the ignition timing correct. I made a new TDC setting tool so that I can get the engines exactly at TDC which is not that simple as there are no timing marks on these cranks. So, put the rear engine No. 4 cylinder at TDC on the firing stroke, then set No.1 cylinder the same, on the front engine; then turn the front engine backwards 90 degrees, pop on the connecting drive belt, set the belt tensioner and then turn the engines so that No.1 cylinder on the front engine is at 40 degrees BTDC. Then turn the distributor by hand until the plug fires on that cylinder. Pop on the distributor drive belt and it should all be hunky dory. Simples! Except the timing disc only fits on the right hand end of the cranks, and you can only turn the engines over on the left-hand side but got there in the end. So petrol in (again), battery connected (again), chokes on (again) and spin the motors over...and the output drive sprocket in the starter shears (again!). Cue locking the shed door and going in for a beer, but hey, if these things were easy there would be loads of double-engined bikes still kicking around. Stay safe.
 #40194  by shasta
 
I know this is a bit like Groundhog Day, but this is the latest starter up-grade. Last time trying to start the bike, the torque proved too much again for the starter output shaft drive pin which sheared once again. To prevent (hopefully) it happening again, the output shaft has gone up from 13 mm to 20 mm in diameter and the drive pin increased from one 6 mm pin to TWO 10 mm pins...break that you *******! Bikers amongst you might recognise a Honda wheel spindle being the new output shaft. Now all fitted back together, a start will be once again be on the cards.
Although a pain in the arse, I'd prefer to have things fail now, than travel all the way to the Pod, unload, push round to the start and then for things to go tits up!
Attachments
Old and new output shafts together
Old and new output shafts together
IMG_a001.JPG (1.67 MiB) Viewed 8938 times
New output shaft with twin 10 mm drive pins
New output shaft with twin 10 mm drive pins
IMG_a002.JPG (1.75 MiB) Viewed 8938 times
 #40195  by shasta
 
Here again, and yes it's a Groundhog Day event once again. Tried to start the bike tonight, and you really have to brace yourself against the torque of the starter which is when the next weak point showed itself.
The main handle sheared one of the 6 mm mounting bolts, bent up and the force caused the 2.5 mm steel plate the grip with the button is attached to, to bend. Great!. Handle now has 10 mm bolts and in the process of making up a thicker plate for it all to fit to. Slowly, slowly, catchy monkey as they say!
Attachments
Bent mounting plate for starting grip
Bent mounting plate for starting grip
IMG_0002.JPG (1.28 MiB) Viewed 8737 times
Long handle with sheared bolt
Long handle with sheared bolt
IMG_0003.JPG (1.24 MiB) Viewed 8737 times
 #40198  by shasta
 
Sorry to see that Santa Pod Raceway has cancelled all of July's fixtures so Dragstalgia will not be taking place this year, the event we had been working towards. Would have taken the bike whether it was running or not, but at least we should have no excuse for the bike not to take to the strip once again next year... 37 years since it last ran at the Pod!!
 #40199  by oily bike bloke
 
Been reading the thread with interest, and you've certainly been busy. Very nice engineering.

Indeed, shame about Dragstalgia.

I don't know if this be of use at all, but on old British singles, to dampen the 'shock' of each engine pulse to the primary drive, a 'spring' (for want of a better term) was located at the end of the crank.
Might a similar device be applicable with regard to your starter / shearing issue?

Keep up the good work!