Yamaha TRX850 Enthusiasts Forum

Hi All,
This is a special request from a newer TRX owner in Thailand...I am going to play with some new Lectron carbs, when they are built. My reason for asking is that I just got out of the hospital from a bad wreck on my CRF. Many months of rehab before canyon charging can resume...new hip, rebuilt wrist.

As I am not near my TRX, and will not be home for another month. I cannot get a couple of dimensions requested by lectron:
* Spigot OD
* Spigot length from head

I simply cannot find this info...can you help somehow?

Much appreciated. Best regards,

Jay

I should have the carbies off the bike tomorrow so if no one comes through with the figures I'll get back to you in a day or so.

Thanks my friend! Saving me again...

Not wanting to cut Cobba's grass but my measurements are:

OD - 46 mm
Length measured from where it attaches to the head - 44 mm

Cheers

Many Thanks Excalibre! Not grass cutting...he has done me right all along. New ignition and other advise. I may be only TRX owner in Thailand, so must rely on Aussie help often. Lectron building me carb toys to play with. First time since my TZ days on 2 strokers.

All good, I won't turf you out on this...



Here is the measurement I have but remember , this is with FCR41's and the not std CV 38mm Mikuni's.
This is from the carbie body to the end of the spigot .
I slipped the FCR's off as I had to replace the inlet rubbers, so measurement was with the carbies not fixed to the bike or without any inlet rubbers attached.
Just the spigot length attached to the carbie was 25.63mm........ ..


Same O.D figure though of 46mm






I recall a figure of 33mm with the spigot unscrewed and detacted from the carbie . (total length including thread)
Handy figure to remember incase you find some FCR's from a Ducati for your TRX as they have shorter spigots and will foul the oil filler pipe on the oil tank with the Accelerator pump mounted on the RHS.
This is not an issue though with TDMR's as there Acc pump is central between the carbies.

I'll email you the photos of the oil tank filler in case lectron need to address any clearance issues.

I think we may have measured different spigots?

I measured the one that attaches to the head.
It was measured from the base of the flange to the end of the spigot, with the inlet rubbers removed.

Cheers

Even better and I'm sure if they had the info from the head to the valve they (as in the inlet port ) they would have all the info they need... I'll measure from the edge of the head to the valve stem tomorrow..

You guys are rockin'!
I am working with Kevin Gilham, the President of Lectron. He is trying to get a good intake runner built to match the carb flow dynamics. You are correct Cobba, I am sure he would use the head to valve distance in his modeling.
If we are a tad off, may not notice much. Then there's the air box mounting and all...hmmm. I guess I will jump off that bridge when I get to it!
It's looking like I owe you all a few rounds already.
Cheers!
Jay

Sanddunes51 put up some excellent photos of a trx head he sectioned to and gives great views of the intake and exhaust port shapes.
Maybe you can ask him if its ok to use the pics he posted.
I was in communication around 12 mths ago with Lectron and they can accommodate for a TPS which is well worth it in my opinion.
I'll email you shortly with some extra pics of the ports.

Unbolted the intake manifold from the head.
The carby end is circular 38mm and the manifold itself is 45mm deep.
But it changes shape from round at the carby end to an oval shape that is 30mm wide and 45mm long where it bolts to the head.



Measurements to the valves where taken with the manifold unbolted from the head and the Verniers sat against the top and bottom of the port.


The top measurements of the valve stem where it enters the valve guide, was 73mm on the centre valve and 82mm on the two outer intake valves.

The bottom centre valve measurement was 84mm to the valve stem ( just before it flairs out and becomes the head of the valve)
The 2 outer intake valves where 100mm from the bottom outer edge of the port.


Intake rubbers are 27mm deep and 10 mm on each end is for mounting to carbies and intake manifold with a 7mm rubber spacer in the centre with a 38mm diameter.

I should imagine the builders would need the carb spacing as well......
(Is it 98mm from memory??)

Spot on centre to centre

Thanks again guys...I have copied this and sent it off to Lectron. I am sure they will do up a great carb setup for me. Results will be slow until I can ride again, but have local kid drooling over the chance to test for me. FYI, carbs coming with O2 sensor/bung and Air/Fuel display. No dyno in Thai mountains...
Awaiting suspension upgrades too. Walter Preisig in Adelaide handling the fork mods and possibly rear shock...may go with Nitron rear however.
Cheers!

always worth loking that the TRXProject site for measurements, that chap has drawn up a lot of the bike and has 3d renderings of an amazing aray of parts.

http://thetrxproject.blogspot.com.au/se ... 3D%20Parts.

http://grabcad.com/library/yamaha-trx-850-intake