Yamaha TRX850 Enthusiasts Forum

Has anybody thought/tried fitting R1 40mm carbs to their engine?

I'm having difficulty getting a set of TDMRs and can't afford a new set.

I'd be curious to see how you get on with this.

I'd love to open the ole girl up a bit but the FCR's are a big chunk of cash.

What I don't get is that a lot of car boys use them on Ford/Volvo engines as sidedraught carbs but they're downdraught on the R1, like the TRX

I'm a child of my generation unfortunately - stripping and cleaning or re jetting, no worries. But trying to do something like this, just making it up as I go along.....id probably not get very far.

Have a go and let know how it turns out lol

dandywarhol wrote:What I don't get is that a lot of car boys use them on Ford/Volvo engines as sidedraught carbs but they're downdraught on the R1, like the TRX

hmm might be an issue setting float heights there

wonder what that does to power / fuel consumption

You could buy a full set of brand new YZF750 FCR41's for the same price as a pair for a TRX (£800ish) & split the cost between you? Just a thought?

A good idea NWS - thought of that one before but is there not just one pumper feeding 4 carbs?

I've been down that road earlier with TDMR40s - someone had split a set of 4 and muggins here bought the pair without the pumper - luckily the German seller took them back and paid the post back..................

All parts/spares are readily available & it's still cheaper than £900 for a TRX specific kit?

OK thanks - I'll look into it. Are the FCRs jst the one pumper and a fuel link to the other carbs?
Could you then fit a pumper pump/linkage etc. to the remaining pair if split up?

PS, answered my own question - the FCRs appear to have twin pumpers, one per pair as opposed to the Mikuni TDMR which appear to have only one pump feeding 4 carbs

Kerching!!!!

NWS870R wrote:Kerching!!!!

,

Ok, ok - it takes a bit of time til the penny drops at my age - life's still a big learning curve

I purchased a set of 39fcrs from a kwaka 750 drag bike (USA ebay) and the set only had one pump.
That said, no big deal to get another pump happening from parts

I split a set of R1 carbs to fit on a TRX a few years ago for someone. There was only one pump on them and it was only the centre pair that were used as they were spaced right to fit the TRX from the start, meaning the two 'end' carbs were spare.

If you decide to split a bank of R1 carbs into two, splitting them down the centre into pairs, you'll need two new throttle rods as they're machined to suit the spacing of the carbs. Maybe Allens could supply them, I don't know. You'd also need new ally spacers and blanking plugs.

It's doable but I think it'd end up being an expensive PITA.

Thanks for your input folks - all invaluable................