TRX 2 - The tuned 850 one!

[dandywarhol]

can you not use a valve from a brake servo on a car? they must be pretty fast acting

Yeah, you could reverse it - should work. I don't get the power loss with big breathers lenny - i'll need to brush up on my tuning knowledge

[coxylaad]

So we are currently acquiring the missing parts to make this into a complete bike.
hopefully we might be able to get it to make some sort of a noise on Saturday

[lenny]

Its called pumping losses. As the pistons move down, air is pushed out the breather. As the pistons move up air is drawn into the breather. The less restrictive the breather, the greater the volume of air moved each stroke and the more power absorbed to do so. The air in a sealed crankcase would act like a spring and draw virtually no power although this would be impractical due to a build up of pressure from blowby. An example of this, although not technically correct is to take a vacuum cleaner or leaf blower and block the inlet or outlet, you will hear the rpm of the motor increase as the load on the motor is reduced. By putting a one way valve in the breather hose air will be pushed out the breather on the down stroke and a vacuum will be pulled in the crankcase on the upstroke and the air will be acting as an efficient spring reducing pumping losses, plus the vacuum formed has other benefits to a four stroke. After the first few strokes the only air actually passing through the breather will be blowby. This will only work with engines that "pump" the crankcase (singles,v-twins,non 360 degree twins eg trx etc)and not inline fours or other engines that do not "pump" the crankcase. All serious performance engines use some form of crankcase vacuum, certainly none use big breathers. Notice I said "serious" engines.

[dandywarhol]

Its called pumping losses. As the pistons move down, air is pushed out the breather. As the pistons move up air is drawn into the breather. The less restrictive the breather, the greater the volume of air moved each stroke and the more power absorbed to do so. The air in a sealed crankcase would act like a spring and draw virtually no power although this would be impractical due to a build up of pressure from blowby. An example of this, although not technically correct is to take a vacuum cleaner or leaf blower and block the inlet or outlet, you will hear the rpm of the motor increase as the load on the motor is reduced. By putting a one way valve in the breather hose air will be pushed out the breather on the down stroke and a vacuum will be pulled in the crankcase on the upstroke and the air will be acting as an efficient spring reducing pumping losses, plus the vacuum formed has other benefits to a four stroke. After the first few strokes the only air actually passing through the breather will be blowby. This will only work with engines that "pump" the crankcase (singles,v-twins,non 360 degree twins eg trx etc)and not inline fours or other engines that do not "pump" the crankcase. All serious performance engines use some form of crankcase vacuum, certainly none use big breathers. Notice I said "serious" engines.

Cheers, I'll sit down to digest that. In line 180 deg. 4s will cancel out to a certain extent, I get that, although once past a couple of thousand rpm the engine is just a big air pump anyway. Vees and crossplanes (the TRX is basically a crosspane IMO) will create more pumping losses due to their bang, bang, wait, bang bang???

[coxylaad]

Ok we have a little problem. The neutral switch blue wire was cut on this bike, the connector has 3 cables on it, checking on here has told me that the other 2 cables go to the cdi unit for ignition retard in the first 2 gears.

The problem we have is we have come to connect it up and the connector we believe it goes into if we put the cable that the blue would go into, down to earth to simulate the neutral switch going to earth we get a dead short with sparks etc.

I think we have the switch wiring plugged into the wrong connector. Can someone tell me exactly where on the TRX loom the neutral connector plugs in?

[dandywarhol]

Sounds like you've got a TDM neutral switch

[cobbadiggabuddyblooo]

There is a 2 pin connector that comes from the side stand switch and there is 1 single bullet connector that comes from the neutral switch on the trx.
Look just above the rear shock reservoir that is where you will find the opposing 2 pin connector and single bullet connector on the TRX 850 loom.
Their function is all a part of the cut out cuircut working in conjunction with the switch on the clutch perch.

If there is an ignition retard in 2 lower gears this is usually done as part of emissions when testing and more so related to later model motorcycles especially with FI as they can reduce fuel being injected to less than 100% and retard the ignition a little to meet their targets .

[coxylaad]

Sorted. Problem lay where the engine had a 3 pin connector from the neutral switch, and the loom I fitted that I had spare from when I fitted the 900 in my bike had the single bullet connector.

[coxylaad]

so it lives again

got to love the sound of those FCR's!

[dandywarhol]

so it lives again

got to love the sound of those FCR's!

............if you ever get tired of the sound...........................

[coxylaad]

I'll bear that in mind Al

right then, currently its firing up but running on 1 cylinder.

We have some new plugs on order, as the ones in there are ancient and have been stood for years.

I am just looking at gathering information before I need it but - anyone got any information on servicing a set of FCR's?

I would like to get the bike running cleanly before I strip it down and start the rebuild. Can you buy service kits for them?

[dandywarhol]

Have a look at the Litetek site
http://litetek.co/

[cobbadiggabuddyblooo]

I made up a few rebuild kits a couple of mths ago. They where snavelled up in a day or 2 and they Included needles and tubes, gasket / o ring kits, and float needle and seats. Cost you about $160 for both carb's to rebuild with shipping when purchased from Webike in Japan.
Slides are set manually and not by vaccum so very rarely need to be re adjusted. Just use the shank of a drill bit to measure that both slide heights are the same.
Std 150 mains usually run a tad rich on a std trx with FCR's..
155-157 mains for kent yam 9's and you'll be pushing it to go over 162-165 mains with higher lift longer duration cams in an English/ Australian climate.(under Tropic of Capricorn )

[coxylaad]

at this moment in time I wont be changing any jets for setup.

the bike was a raced and won in the Bemsee thunderbikes series many year ago so i am sure it will be right.

it just needs to be clean and serviced.

[coxylaad]

New plugs in, she fires up and runs!

doesn't idle very well, and when you open the throttle its not revving very hard, so I guess the carbs need some work. they have been stood for about 6 years now so they are probably gummed up. it seems like the accelerator pump isnt working properly either.

I have read that mins in a bath of boiling lemon juice works wonders, anyone had any experience of this?