Kr1 wont rev + backfire

Luders · Post by **Luders** » Wed Aug 17, 2011 11:18 am

The seals, mains and big ends are done as part of a crank rebuild service. There are additional seals for the crank balance shaft and whilst the cases are split, you could gas flow them if you're interested in getting more power from the engine.

The KR-1/1S engines respond well to having the cases flowed. I believe You're looking at a possible 7-8% power gain, from that of a stock engine.

scooby_hugh · Post by **scooby_hugh** » Thu Sep 15, 2011 6:41 am

Rebuilt the top end last night and still no joy! Im starting to wonder if my crank seals are knackered, does anyone have a way to test?

Luders · Post by **Luders** » Thu Sep 15, 2011 11:19 am

If your crank seals were knackered, transmission fluid would be getting past them and being burnt and therefore you would notice your oil level dropping.

I'm still convinced your original problem sounds electrical related.

maccas · Post by **maccas** » Thu Sep 15, 2011 12:13 pm

If it was me I would try a pair of plugs from a bike that runs fine with them in, as Janbros says new plugs doesn't mean anything, i've had NGK plugs do about 5 miles and be knackered never to work again.

Is your engine properly earthed to your chassis?

You could try running a separate thick wire from a bolt in the chassis to one on the engine to make sure.

Maccas

scooby_hugh · Post by **scooby_hugh** » Thu Sep 15, 2011 1:24 pm

Im not sure it is plugs as it didnt make a difference when i changed them, it was exactly the same, i will try a new earth to be sure, and my transmission fluid is low but its leaking a little out of the kickstart seal

scooby_hugh · Post by **scooby_hugh** » Thu Sep 15, 2011 1:27 pm

The bike only runs for a few seconds and wont rev, when you try and rev it, it will backfire and die, it wont idle anymore and will only start with the throttle open slightly

maccas · Post by **maccas** » Thu Sep 15, 2011 1:38 pm

Check your that your woodruff key is in good condition by removing the flywheel it may have sheared off meaning the ignition timing is out.

Maccas

Luders · Post by **Luders** » Thu Sep 15, 2011 4:31 pm

You'll need a pud puller

http://cgi.ebay.co.uk/ws/eBayISAPI.dll? ... 0718733445

scooby_hugh · Post by **scooby_hugh** » Thu Sep 15, 2011 4:42 pm

Cheers guys, il order a puller!

Howie · Post by **Howie** » Thu Sep 15, 2011 4:48 pm

Assuming I have read these posts correctly, I think I would double check the carbs

Check that they have the correct jets & needles. Make sure the fuel level is correct & all air connections are good. Its the fact it will start & idle (do you need the choke fully on when cold? And what happens when you shut the choke off?) that leads me to doubt the carb set up.

The woodruff key on my Kmx125 sheared off & the bike wouldn't start at all but I would check the rotor/coil etc for peace of mind.

tescr500 · Post by **tescr500** » Thu Sep 15, 2011 10:32 pm

hi you could try getting some neon plug caps to watch the light to check for inconsistancy, check the fuel tap seals and diaframs as the fuel tap works on engine running for vacum, or put on reserve but im not quite sure if this still needs the vacum, if it is electrical sounds its something breaking down under load, check all connections for corrosion including fuse box, but could always be generator which is normally the case my old kr1 used to run on 2 then 1 then 2 and did back fire occasionally this was due to unburnt fuel build up so electrical i reckon cheers

scooby_hugh · Post by **scooby_hugh** » Fri Sep 16, 2011 7:36 pm

my flywheel puller hasnt arrived yet but iv had the bike running, it will run for a while with about half throttle but still wont rev and theres alot of induction noise with the carbs being half open and the revs are only about 1000 or so, it runs on both cylinders occasionally backfiring

where should the vac hose on the fuel tap go to? mines plugged!

scooby_hugh · Post by **scooby_hugh** » Fri Sep 16, 2011 7:37 pm

fao howie, choke makes no difference

Howie · Post by **Howie** » Fri Sep 16, 2011 7:56 pm

Hi Scooby, the vacuum hose should connect to a brass nipple on one (can't remember which side

) of your carbs.

Assuming you have a right & a left carb that is?

Are you also saying that you do not need choke to start the bike even when cold?

tescr500 · Post by **tescr500** » Fri Sep 16, 2011 9:13 pm

i know this is a long shot but check all engine mounting points for cracks and loose bolts, strange as it sounds but i had a ke175 and it had a broken bolt it played havoc with carburation and didn't run very well at all, renewed bolt run perfect, also check for carbon build up in exhausts my mates kdx would not rev for love nor money we renewed oil seals piston rings everything and just by chance we had the top end off again and once rebuilt i said f..k it just take it for a blast went like s..t of a hot chrome shuvel, we put the exhaust on then back to the same would not rev, so we cut the exhaust in half and half and half we found a huge lump of carbon build up a hole the size of a pea gases no where to go and the bike wasn't that old either, and last but not least not that we do this anymore when we were young we used to use a bit of stocking on the back of the carb for a filter, didn't used to last long and some ended up wrapped round the reed blocks and believe or not got stuck in ports as well and the bike was a ts185er, hope this helps or at least a few good stories from the ole days cheers wayne.