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CR750 Running (or not running!) issues
philward:
--- Quote from: MarkCR750 on November 27, 2018, 10:12:14 PM ---Ok, mine started to get difficult to start, I found that giving the throttle a couple of sharp twists to make the accelerator pump squirt fuel into the intakes and then pressing the starter button regained instant starting, I think maybe my primary circuit is blocked, really must get around to taking carbs off and sorting, obviously you can’t try that because you don’t have an accelerator pump.
First I would try new plugs because it’s easy, but I think you’re issue could be fuelling , so I would..
1. Check the choke mechanism is working correctly
2. Check float heights and check that floats are not Punctured
3. Check the needle valves are seating/operating correctly
4. Check the carbs are receiving fuel from the tank and the tank isn’t forming a vacuum.
5. Give the carbs another clean.
Then, check the inlet rubbers for leaks.
Then alter your float heights away from the standard setting, if it gets better or worse you might be on to something.
Then because my bike ran badly with Pods until I grafted the original intake trumpets onto the front of them which makes me think pods are a bit crap I would get some velocity stacks, this doesn’t fit with your problem suddenly appearing but I think you’ll find the bike generally runs better with stacks, plus they look nice!
Also check your timing with a strobe gun so that you know the advance/retard is working
It will most likely be none of the above of course 🙂
--- End quote ---
I've tried 1 - 5 Mark. The foam pods I've fitted have a smooth transition inside without the step on normal pods (read your post!). Probably will be going for stacks longer term and adjust settings accordingly. Have strobed and advancing ok as per Boyer instructions.
I'm leaning towards the way I've balanced the carbs - they are definitely balanced (on vac guages) but with all flooding on all 4 pots (after I balanced them) I'm wondering whether the needles are set 'too high' at start up - if that makes sense. I have an original genuine Honda workshop manual that I'm sure says you balance them using the air screws (? - will re-check manual) - planning to bench balance them measuring slide cut outs distance (as I originally did when it started easily on first start up) then re-balance.
Just waiting for D7 plugs to arrive and try them.
I'm waiting for
MarkCR750:
Ok Phil, I’m never sure at times like this if it’s frustrating or interesting, both I suppose, first principle in trouble shooting is “what did I do just before it went wrong? “ so could be something that happened during the balance work if not the balancing itself (which is unlikely to the cause of the poor starting, but I know you know that :) )
philward:
I agree - may be air screw adjustment relative to the balance of the carbs - may get time this weekend to have a look (barring Grand children arriving! I'm not too stressed about it - as long as I get it sorted by the spring!
CR750:
How much & how long have you had the fuel in the tank ? this could be your problem
Try draining the tank & fill it right up with a good premium fuel & then add some stabiliser for winter storage, if this sorts out the problem you then need to start it up every month or so until engine is warmed up. hope this helps
philward:
I've only been putting half a gallon in at a time as I have been waiting to get the CR replica fuel tap back from the guy who makes them (as it was leaking) and knew I would need to drain the tank. I have a cr250 motocross tap on at the moment (its not a tap issue as I've had that fitted since start up).
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