Tlr200 Carburettor Rebuild

[esteve]

I've started this post because I'd like some information on a replacement Needle Set and confirmation of what jets are best. However I'm providing a preamble in case it's of interest to others.

My TLR200 is circa 1983/1984 ? (registered in UK in 2009 on an "A" plate and shows first registration as 1/1/1984) - Frame number 1004•••. The red/white/blue tank model - its not NOT a Reflex

The carburetor is a Keihin PW22. The ID on the flange is 660C |B|VI= (660C on RHS of Flange, |B|VI= are the symbols on the LHS; the B is actually in a "box" but "| |" is the best I can do on a keyboard). For parts ordering the important parts of the ID are "660C B"; only the first symbol from the LHS group is required. RHS and LHS refer to the position when on the bike, not looking at the front of the flange)

I have another identical carb as well that is from a bike with Frame number 1019••• (imported from Japan in November 2000 by D&K in Staffordshire)

Both carburetors have the same jetting

Main Jet 98

Pilot Jet 40

Needle circlip: second groove from top

Needle ID: stamped 2FA

Slide: 166C 2.5

.....................so there is a high probability that these are standard factory settings for the Japanese market (which year(s)?), or a common pre/post delivery rejetting?

In general the performance with these "660C B" carburetors is very good with a clean pick-up and only occasionally have I experienced the "cough, stall" but when it does happen it is very frustrating.

I've cleaned both carburetors in an ultrasonic bath and they are now as good as I can get them without replacing the needle and needle jet (which might have some wear). In combination with a DEP exhaust (having previously used the standard TLR200D/E exhaust) the performance seems a bit better than before the rebuild but maybe there is room for improvement? I have an almost as new body from a carburetor taken from a Reflex that I want to rebuild to a suitable specification in the hope that will provide optimum carburation.

The Reflex carburetor (ID on flange = P08A |A|) body appears identical to the 660C |B| body apart from, on the Reflex carburetor, projecting lugs around the float bowl clip and a threaded boss on the base of the bowl; 660C on left, P08A on right (note the floatbowl breather/overflow set up):

The jetting for the Reflex carburetor is:

Main Jet 92

Pilot Jet 38

Needle position: only 1 circlip position

Needle ID: stamped 6LC ......is this the standard Reflex needle or one from the 16012-KJ2-305 kit popular in North America?

Slide: 166C 2.5

I've no idea how this performs but comments about this specification are not favourable, especially with regard to the 38 pilot jet which most people seem to find is too lean. The 6LC needle appears, apart from only having 1 setting, to be identical to the 2FA needle in terms of diameter versus length; ie the tapers are identical. The single circlip position on the 6LC needle equates to groove 3 on the 2FA needle which is a richer setting (at wide throttle openings anyway) compared with a 2FA needle on groove 2 - I had the impression that Reflexes ran weak as standard as the general opinion is that the needle needs to be raised, usually with a small washer?

I'm now at the stage of looking for suitable genuine (known size) jets and a slide needle to bring my Reflex carburetor to either the same specification as my non Reflex carburetors or something better.

A TLR200 carburetor rebuild kit I acquired is non genuine (the jets and needle are unstamped; no sizes, no "K" star logo) although the gaskets, o-rings, drain screw, float valve, airscrew and tickover screw appear to be usable. If you are going to use any non genuine Keihin parts be VERY careful when it comes to the airscrew and tickover screw springs. In the picture below, from top to bottom: Reflex airscrew (with cap), Reflex airscrew (no cap), Genuine airscrew spring (.6mm wire), Genuine airscrew (worn tip), Non-genuine spring (too long and 0.7mm wire; same length as the spring for the tickover screw), Non-genuine airscrew (slightly longer but taper is the same):

Using the overlong and stiffer non-genuine airscrew spring would cause damage. In this particular rebuild kit the airscrew and tickover screw springs are identical and I wouldn't advise using one for the tickover screw either because although they are the right length for the tickover screw they are much stiffer (0.7mm vs. 0.6mm and temper?) than the original part and would strain the threads in the carburetor body.

I have a parts catalogue dated 1983 for the TLR200D and TLR200E models. The photograph for the model shows a TLR200D which has a white tank, round headlight, 35mm forks (bulge on sliders), alloy front brake arm (so 95mm ID drum) and an exhaust that is not the Reflex type, i.e. a small OD tailpipe compared to the fatter Reflex type).

It lists the markets for the TLR200D as:

AR - Austria

BH - Belgium

F - France MD09 - 5000009~ and carb type 660C |A| (the |A| is the first character of the ID on the LHS of the carburetor flange)

H - Netherland

and for TLR200E

E - England

NZ - New Zealand

SW - Switzerland

The specification for the carburetor for all but the Swiss model are:

Main Jet 98

Pilot Jet 42 (vs. both my non Reflex carburetors use a no. 40)

Needle Set, Jet part no: 16012-331-771 (kit; needle + jet + clip + retainer)

The Swiss model uses Needle Set, Jet part no. 16012-KJ2-741 and a no. 38 Pilot jet

Questions...................

I have obtained an OEM needle set 16012-331-771 and the needle is stamped 273005, so that adds another element of uncertainty as to what is the best needle for trials. The bag was open so maybe it is not correct for the set part number. The 273005 needle has a narrower taper than the 2FA needle (and seems to be the same diameter/taper as the non-genuine needle in the rebuild kit I discussed above). The image below shows a 2FA needle and a 273005 needle bottomed out in identical holes in a disc (its a button...) the fatter needle (with the circlip) is the 2FA. The 273005 needle would give a richer mixture than the 2FA needle (the ID of the needle jets appear to be identical) at wide throttle openings but just off idle the diameter/taper appears to be the same (using my "button box" as a source of go/no-go gauges - and swapping the holes I'm placing the needles in to make sure the holes are identical). Its not easy comparing a needle with some wear, even if imperceptible, with a new needle of a different taper.

The 331 model code indicates a part for a SL125 K0/K1/K2 model.

• Can anybody confirm that 273005 is the needle in the Needle Set 16012-331-771?
  
• What is best, a 2FA needle or a 273005 needle?
  
• Any other recommendations for a needle/needle jet set?
  
• Pilot jet; 40 or 42? WIth a DEP exhaust system would a 42 be better?
  
• Main jet: I've seen posts about fitting 100 or 105 main jets but I presume the main jet is not that critical as it only controls the last part of the range of slide travel?
  

Thankyou

Edited October 14, 2013 by esteve

[bashplate]

Hi Esteve, some well spotted observations on the carb differences, your methodology(is that a real word?) will give the TLR guru's some thing to ponder on and I'm sure there will be many others with the same questions as yourself. Looking forward to some definative answers.

[maxbikes]

I would keep it bog standard,use original carb and make sure all very clean,dont mess with other jets,leave needle on second groove down.check flange on carb is flat on head,if not use wet and dry on a piece of glass to get flat.If you want to waste time why not rebuild spare carb with rubbish new parts and try bike with either rebuilt carb,dont take long to change them.i bet the original set up carb will run a million times better.

[esteve]

check flange on carb is flat on head,if not use wet and dry on a piece of glass to get flat.

Its a good point to check the carburetor flange is capable of sealing and the key to that should be a correctly sized new o-ring. Fitting an oversized o-ring will cause distortion, to the extent that the slide can stick in some cases because the carburetor should be flanged up "metal to metal" to the manifold/insulator and the flange will bend about the oversized o-ring. If the flange is distorted and material is removed then part of the o-ring groove depth will be reduced; be careful.

The groove in the carb is 2mm deep and ~3.4mm wide. The correct replacement o-ring is ~2.5 mm diameter cross section and 29mm ID (size not given in the parts catalogue as it is part of a kit; these are my measurements) and when the carburetor is flanged up compression of the ~.5mm of o-ring standing proud of the groove forms the seal and it can expand into the 3.4mm wide groove. However on the carburetor below somebody replaced the correct o-ring with a 3.4/3.5mm cross section diameter o-ring so when the carburetor is flanged up with the manifold there is nowhere for the extra o-ring material to expand to and the flange will bow about the centre of the flange and the distortion will either have immediate effect or as in my case creep through the body of the carburetor and cause slide sticking (and air leaks) about 2 years later.

Carburetor flange with correct 2.5mm diameter o-ring:

Carburetor flange with oversized o-ring completely filling the groove:

The seal between the Manifold/insulator and the head is also critical. An up to 30 year old o-ring is liable to harden, crack and leak as the witness marks on this manifold show:

The correct o-ring size for this joint is 33.5 x 3 mm (Honda parts catalogue). The OEM o-rings seem to be nitrile? I've thought about using viton (re ethanol content in fuel) but these tend to be a bit harder.

With the engine in the frame the only way to remove the carburetor is to detach the manifold/insulator from the head so plan ahead and have spare o-rings to hand.

A good tip is get a bike running and hot before trying to undo engine bolts such as those for the manifold/insulator; the same applies to valve covers, timing cover plugs etc. so think about slackening anything off after a trial- just make sure the engine is stone cold before you replace any threaded item...

Also, there is not much space to get at the bottom 6mm bolt for the manifold/insulator and you need a combination spanner with a shallow angle ring to fit the 8mm head properly (if it hasn't been chewed up already...then a vice grip and a hot engine may save the day and overcome the friction due to 30 years of bolt corrosion). If the bolts need replacing then to conserve the threads in the head I would recommend using Honda parts, 96000-06020-00 "Bolt, Flange, 6 x 20mm" and not some generic bolt with poorly machined threads....and apply a light smear of "Copaslip" to the bolts when reinstalling, not a great gob of it or you could create a hydraulic lock in the hole. Don't overtighten, its only a 6mm bolt.

Edited October 12, 2013 by esteve