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Post by re5anovice on Jan 10, 2019 12:47:22 GMT -5
The bike starts quickly and runs great to 3,250 rpm roughly then hits a bad flat spot with vibration and snatch then at 4,000 rpm it's smooth again.
It means that open road cruising is awkward, i have to go slower than i want or too fast.
Any ideas what could cause that?
Would any regularly used modification maybe help with this?
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Post by wayne on Jan 10, 2019 16:00:12 GMT -5
This is a completely standard issue resurrecting an old RE5.
First of all, the vibration is normal. It was there in the factory prepped test bikes the journo's rode back in the day. It's an engine harmonic peculiar to some rotary designs and you will never get rid of it. It feels almost like a shudder that runs through the bike. Call it character and don't worry about it.
The flat spot or hesitation is an issue with carb set up. It occurs during the transition from primary to secondary throat. It can be cured. Search this board, there's a tonne of information on it. Basically, you need to thoroughly clean your carb (meaning ultrasonically). Also give it a good once over to make sure everything is where it should be (brass plugs etc) and that the accelerator pump actually works (and if not, fix it). Read up on everything re set up but Suzuki Bulletin 9 is probably the best overall guideline.
A bandaid solution is to run a bigger primary jet. Try a 100 to start and fiddle from there (90 or 87.5 is stock). However, do this only after you've done the carb clean, proper set up, correct air filter, points set, timing done. All the basics.
The bikes can be set up to run without the flat spot/hesitation and once you get it right, it will stay right.
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Post by wayne on Jan 10, 2019 16:29:18 GMT -5
PS If you do get everything done and get to the primary jet change idea, it takes 5 minutes, even at the side of the road.
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Post by Jess on Jan 10, 2019 17:58:49 GMT -5
My 2 cents...
The carburetor is not clean.
Unless you know where the air filter came from, replace it.
YMMV.
Best
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Post by re5anovice on Jan 15, 2019 16:13:23 GMT -5
More to come later but there are a large number of reasons the bike was so stuttery and vibratory and felt quite awful to ride in all honesty. A very learned RE5 expert from Stafford has the bike and is very kindly working on and replacing many things to get it as near to right as possible. The bike had a lot of faults that made running cleanly impossible. Here's hoping he can get it sorted and i have plenty of faith.
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Post by re5anovice on Jan 22, 2019 7:09:57 GMT -5
Answer was 11 different things wrong powerplant-wise with the bike, so thanks for the inputs. Yes the carb was dirty, the jets were partially blocked, the advance/retard wasn't working, the cables were stretched and poorly adjusted, the diaphragm was torn and more besides. No wonder the poor thing ran like a sack of of the dark stuff.
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Post by re5anovice on Jan 24, 2019 2:29:16 GMT -5
The sump oil was also way above the normal amount when i checked it.
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