another xbr project but needs speed

[onthecheap]

Hello everyone. Newbie to the site here. I have a few single lungers in the garage 1 Japanese and the rest are old Brit's until now. Couldn't resist a bargain when an XBR motor was offered to me. So what to do with it ? chuck it under the bench for 12 months is what happened. After stubbing my toe on it and shifting it umpteen times I decided to do something with it.
Going to use it for hillclimbing, twisty sprinting and a few club meetings. As is normal for me I start to collect all sorts of stuff before making a start. So I have found a rolling chassis of sorts, seat, tank, fairing, etc.
 Now the motor. Having read many posts on here I have a plan of sorts but I intend to keep it as a 500. As you are all aware the motor needs a serious diet. In one of my many boxes I have found a new self generating ignition from a speedway motor so that will save a few kilos by junking all the Honda stuff. The starter motor and kick start mechanism can also take a hike.
A head job and a Joy cam seem the way to go from what I am reading along with a big carb. Got a few Del Orto pumpers kicking around so that is sorted. I have also read that the clutch to use s off a xl 600 which is lighter and the primary is also different. Am I also right in thinking the balancer shaft gets machined ? As for pipes I will make them myself but 2 separate or 2 into 1 ? diameters ? lengths ?
So lots to do but at least I am aiming for next season not the end of this one !
Any advice gratefully received and I hope I can do some sort of picture progress.

 

[SteveC#222]

Hi there, welcome to the forum.

Sounds like you have big plans for the XBR.  I have an article from thr old Thumperpage about race prepping the GB500 ( basically the same) including bits on modding flywheel, gearing, CDI & plans for a race exhaust. If you PM me your email address I'll send you a copy across as it doesn't seem to be online anymore.

[onthecheap]

Thank you for your reply. it sounds the stuff I am looking for. How do I send you a e mail via the site to contact you please.

[SteveC#222]

email sent.

[JOOLZ]

Sounds like an interesting project, can you post a picture of the speedway ignition system, I may fit one to my bike it would simplify a few things

[onthecheap]

JOOLZ the ignition is really simple as even an electrical numpty like myself can sort it. It only has 2 wires and you don't need a battery as it is self generating. Cant remember the exact price but it was less than 200 notes. Will post a picture later when I dig it out of the many boxes that seem to breed in my workshop/shed/garage/storage unit !

[onthecheap]

Bit of an update. As I am still collecting stuff I am doing what I can as and when. So the frame forks wheels etc are what I have the most of that is where I have started before sorting the motor.
After a bit of buggering about making engine plates in ply I have the motor where I want it to be in the Aprillia RS 125 frame I also have some bits to weld on the frame for bars to run to the front of the engine. The rear end was a bit more agro. As the Aprillia has a left hand chain run ( bloody Itaians ) the standard swing arm is no good sadly. So looking around I have managed to graft in the rear end of a Yamaha 125 - I think they are called YZF - who cares it fits ! The standard Yamaha whee is in at the mo while I sort out spacers for the Aprilia wheel. Eventually I want to fit spoke wheels.
When I have made the engine plates I can get on with the motor.

[onthecheap]

Well the project is still in the boxes/piles stage despite the engine plates being sorted I have other stuff to do - workshop extension so this will be done in the next few weeks then work can start in earnest on the Honrillia project.
A question on oil capacity though. As I am making my own oil tank and adding an oil cooler along with larger diameter oil lines I am considering 3 litre as the capacity of the oil tank working to the theory that with more oil on board it should stay cooler. Thoughts welcomed on this.

[guest564]

I don't recall the amount of oil required but I do recall many people having issues with the oil system 'wet sumping' when different frames or oil tanks were used. The lines on the stock tank go upwards before going down to the engine - that may be the key to avoiding the problem.

[onthecheap]

A few pictures now I am about to start in earnest. I have collected bits for long enough and seem to have most of what is needed. The frame and forks are from an Aprilia RS 125, due to the fact that these bikes use a Rotax motor ( drive side is on the left ) the original swing arm is sadly no good. So the rear end is from a Yamaha 125 along with the rear wheel and caliper. I think it is a YZR 125. a bit of buggering around with angle grinder, lathe, mill, welding torch, skin etc will see this in place with dural engine plates. The front engine mounts will be simpler but must get the rear in first.
The engine has to be the heaviest single I have ever come across so a serious diet is needed. I have a Triumph twin engine on the bench also which is no way as heavy. I will strip the motor down to bare cases, barrel and head to get it to fit.
Lots of work to do particularly in the engine department but hey ho its only time and money.
Big bargain so far has been a complete set of Aprilia superteen bodywork - fairing, seat, undertray, mudguard, screen, dummy tank, tacho and mounting bracket all sprayed in 2 pack for 104 quid - result.
Pictures wont load it says file too large ? means nowt to me ( computer philistine ) any help appreciated.

[iansoady]

Pictures too large? Use something like pixresizer (free) that does what it suggests.

https://www.webdezign.co.uk/useful-guides/how-to-resize-your-images-using-pixresizer/

[timbo]

Sounds a great project. Pics have to be no larger than 250kbits to post on the site, I think. You can resize by going to Edit 

[silver]

You say you are using Aprilia RS125 frame? I am using RS125 wheels on my MZ project, but I had to reverse the rear wheel to get left hand chain run, unless the tyre was on backwards. Is yours with the five spoke Grimeca wheels?.
All the best with it, you can take a look at my project on here.