Hi guys – hope someone out there can help as i cant find anything using google

Installed a HSR42 carburettor on my 1996 1200 sporty and I cant seem to get the bike started using the choke. Bought the Mikuni choke cable and installed it and check it several times but no luck. If I give it 2 throttle twists it starts and as long as I’m feeding some throttle I can keep it going but it dies as soon as I stop twisting the throttle.

If I could get the bike running I can systematically adjust the system but I cant get it going – any ideas.

PS I haven’t replaced the inlet manifolds seals yet but I did replace the seal between the carb and the manifolder. Bike was working fine with the CV carb????

Thanks in advance

45

Try to google hsr42 and look at the mikuni website. They have a great page on tuning and fault finding. There is an issue with choke cables, but I think that refers to the standard choke cable.
Silly question, have you checked that the throttle on/of cables are adjusted properly and the right way round? Also, try adjusting the base idle screw up. The mixture screw would be about 2 turns out from seated as a starting point.

Taff

Thanks for your reply

Read the manaul and been on their website - non of the provided trouble shooting addresses the non-starting/ choke issues I'm having.

mixture screw - 2 turns out as per the manual

idle screw -  various postions to change

throttle cables correct - but I'll check the adjustment tonight.

Seems like there is no fuel coming through - becuase if I give it 2 twists she fires up and then dies once the fuel is used up

Maybe the float is stuck ?????? I dont know????

Thanks

45

 

 

An usee the slide moving up and down when u pull the throttle? Sounds like u are only getting fuel from the accellerator pump.

Spot on Taff, slide move up and down but fuel is only getting squirted in from accelerator pump.

What now, float stuck?

Cheers

Could be. but the pump is fed from the bowl. Is the needle moving With the slide? In case it has come loose.

And read the section about which parts to use with the mikuni choke cable. Just in case.

starting to think it might be the vacumn/ voes line that is folder closed.

the thing that gets me that even without the choke it should fire (maybe run like crap) and it should fire - which of course it doesn't

anycase thanks for the pointers Taff

cheers
45wl

So by process of elimination:

Slide and needle move.

Fuel is only being provided by the fuel pump.

Disconnected the fuel tank pressure release tube - no change

Disconnected the VOES and she fired right up - can someone explain this to me
even if the VOES is faulty would this prevent fuel from entering the carbi?? vacumn lock??

Cheers
45

If it worked with the old carby, cant see why it would just stop. Is the tube connected to the correct port on the carby? There is a vent tube that just sits there and does nothing, a vacuum piep, and an overflow tube. I think. Check they are correctly connecten. You might be on to something there.

Thanks

I'll play around some more this weekend and report back

Cheers

So I got back onto the project this weekend - and she f@#$ing b!tch!@$ wouldnt start/ fire at ALL ......... so its back to basics, removing everything, renewing inlet manifold seals, cleaning carb etc etc - unless someone has a brighter and less frustrating way forward ???

Cheer
45

Why not put the old CV carb' back on as a quick test.
What's the history of the Mikuni ?

Hi Speedzter

Yeah that's the idea - return to stock and check ... then f!$@! around with the Mikuni

Mikuni HSR42-11 is brand new and should have any issues except tuning - if I could get the bloody thing running I could tune it but I just cant seem to get it to that point.

At the moment I'm frustrated and I learnt at long time ago just to walk away until I'm in the "right" frame of mind to fix the problem lol

Cheers
45

Did you happen to check if the float bowl was filling with fuel OK ? should be able to drain about 1/4 cup.
I have heard of them coming out of the factory with the float levels screwed up.
Also make sure the idle screw is starting to lift the slide, but not to much !
I've fitted a few mikuni's and never had a problem, apart from needing fine tuning.
Another thing to try is use an external fuel supply. Does the sporty have a vacuum fuel tap ?

Thanks mate!

Valid things to check! I'll get onto these in the week and report back.

The sporty has the stock fuel tap with the vacuum line connected to it - initially I thought this was the culprit, but I removed it and still nothing. Only when I removed the VOES line did the choke work.... but as previously stated when I went back to start sorting things out she wouldn't fire up at all.

Cheers
45

Im assuming that you have a spark and of course, that there is fuel in the tank!!!!!!!!!! Still thinking along the line of vacuum pipes somewhere. Do you still get the squirt of fuel from the accellerator pump when you crack the throttle? If not, the carby may not be filling up the float bowl. In which case fuel tap and float level is suspect.
Keep us posted.

yes mate, spark on both cylinders, new plugs and a full tank of BP 98 oct :-)

Still getting a squit of fuel from the acc. pump

This sh!t is pissing me off no end - it will probably be a loose wire or something

Cheers
45

idle jet would be around 25 or 27.5 i think 30 could be on the rich side of things, main around 170-175   , check fuel bowl flow & level 

also adjust acc pump so it only just works   or spray's