Hello Loek,
i use Dellortos with a pump, so i can not tell what it is like to have non. But i think while accelerating from lower revs the mixture can get very  lean for a moment when you pull the throttle full, especially with singles or big Twins. This might be no problem, if you be "delicate". So the bike is surely driveable, but: it´s more fun with the Pumps, and maybe you don´t want that guy next to you on track to be much faster out of the corner,
Ali

Unfortunately I don't have a comparison on TR1s (I run Mikuni VM38s without an accelerator pump on mine), but I do quite a bit of work on Guzzis, both with and without accelerator pump. As Ali said, you have to be more delicate and roll open the throttle and can't just crack it open. You can counter this a bit by running a richer pilot and needle setting, but this will of course have other side-effects, most notably from a racing perspective: The bike feels a lot less "snappy".

Hope this gives you a bit of an idea.
Greg

Hi Loek,

I think that Ali is perfectly right. Big singles and twins need some more time to rev up from low revs (idle and little above that range) and the mixture might get lean when opening the throttle immediatly.
The accelerator pump should rich up the mixture in that phase. But once  the engine has reached its maximum torque and revs further to the limit, the main jet and the needle jet should control the mixture.
When you only drive on closed tracks you will mainly use the middle and high revs of the range which means, that you do not need the accelerator pumps.
I have tested it in Oschersleben with a big Honda 650 single and get the best throttle repsonse from a well set Mikuni TM40 without pump.
If you need the pumps to get out of a curve you should better change down a gear.

Just simply test it on the track by removing the actuator lever inside the slide cover. An easy job with Dellortos.

I am just also fitting a set of new Dellortos to my TR1 engine, together with some other modification. But mainly for road use......and therefore I start with pumps and will see what happen.....


Do you have a picture from your bike in a side view?


I have also tried  -just for fun-  to fit the TR1 engine in a single cylinder Egli Frame, but ist too tiny.  A SR500 will fit easily......

The second pictures shows my work on the TR1 so far.....

   

Hi Loek,

I have been gone through your dutch blog, very impressive work you have done !
Are you a professional for milling and turning work or do you have a well equiped "hobbyiest" garage?

My Egli frame and bike is made for early eighties supermono singles like SR500 or Honda XBR500. It is the only Egli frame which is stressfree to the engine. A batch of 32 streetlegal frames have been build between 1982 - 1985.  
To have some more "fun" and grunt I am planning to integrate a Weslake twin engine. I am aiming for 150 kg / 850 ccm / 80 PS.
But thats another story

When installing the Dellortos do not forget to drill a M5 or M6 threads into each inlet port.
You will need them for balancing the carbs with vacuum gauges. The Mikuni manifolds do not have any connector for balancing.

Hi Sepp,

Thanks for your reply! Is it the PHM40 or PHM41 that has a new version or both? I'll ask the supplier. He is the importer for dellorto in the Netherlands so he should know I'll take the advice on the accelerator pump. It can be easily disconnected at a later stage when we want to. And with future upgrades on the engine... will the 41's be the best option?

Then about the endurance... I didn't know about the classic-endurance.de version... I looked ad the website and found the name of Sascha. The same Sascha as classicendurance.com Whatever, starting in a slightly friendlier version of racing is a very good idea! So thanks for the tip! We'll contact the organisation for sure.

And about the engine... it has standard internals for now. Dellorto's, exhaust and an ignitech are the current upgrades. But then what's next on a standard engine? 750 heads? other camshafts? porting the standard heads? These are my first steps in engine tuning and I Like to be able to do all the work myself. So tips and advice are very welcome

I've got al the (standard yamaha) parts for the XV1100 - TR1 engine combination.... but that will take a while to build, surely not for the coming season. I'm not sure on what pistons to run in that engine? Standard seems good to me, or even the XVS1100 versions?. I'm not very sure on all the american piston makers with their magic numbers and have no experience in "designing" my own to be custom made...

Best regards,

Loek