RB270 Project

[Solid Air]

Fat Mamba exhaust, with modified stinger (ID of 30mm) to clear the extras gasses that will be created.









Mikuni TMX 30mm with a modified bell mouth to match the ProPorting elbow.

[dickie]

I heard those ramair filters are much more restrictive than breathe sweet and casa powerflow.

Ive no personal hard facts. Do you know?

[Solid Air]

I have used Ramair filters for years and never had any problems with them, haven't used the others so can't compare I'm afraid.

[Solid Air]

The Fat Mamba exhaust is now sorted with its new 30mm ID stinger section. The tail pipe has a bespoke outlet, made by my best mate Viv of Raven Motorcycles, a larger baffle tube has been made, courtesy of Mick Abbey, and the silencer casing just needs finishing off to mount it onto the exhaust.

Sadly we ran out of time as we had to get to Teesside for the BSEC race (where we took second place in race class ) so the carb set-up and dyno will have to be done another day. In the meantime time, the engine has been started with a temporary standard tailpipe, and sounds great! I am going to get the bodywork fitted so that the dyno session will be the last thing to do before Small Hours is finished.

[Adam_Winstone]

Looks great!

[Solid Air]

Thanks Adam.

[Tony Hart]

Looks very impressive Mark.

[dickie]

Great thinking to not just buy a regular pipe. I wonder how much louder a 30mm silencer will be?

[Solid Air]

Not modifying the stinger on any exhaust for this engine would be asking for trouble, with the gas build up and the extra heat made from that. Going by the information available 30mm ID should do the job, fingers crossed. Time will tell regarding the noise level.

[Solid Air]

The engine build is now complete, I just need to finish the rest of the jobs done to finish the job

Dyno day up at Raven Motorcycles near Darlington yesterday, and very productive it was too. Once it's all built, I will get a few running-in miles done then head back up north for fine tuning and step-testing.

At peak power, between 6,500-7,000 revs, the numbers are 26 bhp and 21ft/lb of torque.

It would have been possible to have tuned the barrel to get the numbers a lot higher, but it was a grunty touring engine that I was after. It has been built for a purpose, and to my requirements. I also wanted to be able to use a bigger than standard crank to reduce the risk of twisting. The Casa Case allows this and we have actually used a 70x120 item, this gives the higher cc while still only using a 70mm piston. The bore and stroke are intentionally square and the state of tune has been kept purposely low for our requirements. This will all hopefully give me a good level of reliability too.

Cheers, Mark

[Adam_Winstone]

Excellent!

Yes, IMO it is the rev range at which you make power and the spread of power that matters, "At peak power, between 6,500-7,000 revs", and this is very useable and does not stress components.

As DT and others have shown, it is reasonably easy (not for me though LOL) to get higher BHP at higher revs but that result in a very different ride and performance scenario. Indeed, 5-speed box development has been frantic over the last 10 years, not so much as to provide a more civilized ride to touring engines as to allow tuners to keep higher BHP engines with narrow power bands in the power. Your motor is just the opposite, a low revving motor with excellent broad spread of power, which could happily span the ratio gaps of 4-speed boxes.

I look forward to you telling us what a joy it is to ride

[Solid Air]

Thanks Adam. Fingers crossed and I will report back, a little blat up the road yesterday was very promising though. I have fitted a 5 speed gearbox but questioning now whether it will be necessary. Only one way to find out there. Cheers

[Covboy]

Looks Brilliant Mark - well done - you and viv must be very proud of the engineering involved.
Looking forward to seeing and hearing it !

[Solid Air]

Thank you Steve! Yep, we are both like a couple of proud fathers, very happy with the new arrival hopefully see you soon with it.

[dickie]

That power curve looks like a 4 stroke! Very impressive.

As you and others have said, I doubt you need a 5 speed. My RT230 reed doesn't need one. I suppose it might make it better, but could just end up needing more frequent gear changes which would detract from the improvements you've made with the square configuration.

Very nice work.

[Solid Air]

Cheers Dickie. Yes it is a good curve isn't it, sounds very much like a 2-stroke thankfully