[CleanerCarpets]

Hi,

I have a Honda GX390 engined carpet cleaning machine - it powers a pump and blower

Ive recently bought it and i have been servicing it to go on the van.

I bought a cheap tachometer off ebay so i could see what revs its giving in case it needed some tweaking - this is the tacho -http://www.ebay.co.uk/itm/291281841858?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT

I fitted it today and its telling me that on full throttle the way it is at the moment i am only getting 2k revs. There is adjustment on the throttle stop to get more and probably on the pilot screw on the carb but i am worried about tinkering as its seems a lot short of what it should be at which is 3600 revs. It seems to be revving higher than 2k but i thought these little tacho's were actually pretty accurate.

I just wondered if any of you guys have the same engine on a pressure washer set up and fitted a similar tacho?

Any advice would be great.

Jason

[BDCS]

Where you you ? Does it sound like its revving the right amount ? Is the throttle against the stop ? Is 13hp enough for what you need ?

Are you sure the tacho is a fourstroke on and not a 2 stroke one - the 4t one fires every other rev and the 2t one every rev so the 4t one doubles the fires to give revs - if you get my drift

[CleanerCarpets]

hi,

yes 13hp is fine, the throttle is all the way to the stop but i can wind the stop screw out and get the throttle over more, but not sure if that would get the tacho upto 3.6k

its sounds likes its revving higher than 2k at the moment but its hard to tell by ear. Ive always had bikes and have a Fireblade at the moment but working out these little engines for revs seems tricky

my gut tells me its revving higher than the tacho says but i can't see how these little tacho's could be that far out. If it wasnt working i would expect no output, as its picking up a signal from the plug i would of expected it to be fairly accurate

[BDCS]

Unless like I said they supplied the wrong one - try it on your fire bandit as a known reference

[CleanerCarpets]

yea thanks mate - that was what i had thought was best to try today

get todays jobby done then have another tinker with the machine later

[CleanerCarpets]

ok - had another go today

i can't get at the plug cables on the bike without stripping the tank or loads of plastics off and my van and car are both diesel   

i tried it on the machine again and made sure it was all wired dead on - same thing showing max 2k revs with throttle and throttle stop full out - it has no more to give

done a load of googling and i think the tacho is actually giving me half the reading it should cos of the firing

the tacho advert on ebay says its for all 4 stroke engines, but the way the engine fires will change the pulses read by the tacho. I think the tacho is actually set up for a 4 cylinder 4 stroke engine, not a 4 stroke single cylinder like mine hence getting half the reading

i think i need a tacho that adjusts for the firing like the Tiny Tacho but they are harder to get in the UK

do you think my thinking is right?
 

[Mike Halliday]

Another way to check on that machine is to feel the vacuum it's creating at 50ft,  if it is only revving at 2000rpm then  you will have quite poor vacuum (problem equal to a small portable)

[CleanerCarpets]

Aye up Mike!

Thanks for that, I am going to run the machine with some hoses next week, going fishing tomm. I've had hoses on it before to test but it wasn't a good test - the machine had leaking hoses, throttle wasn't staying open, wrong blower filter etc etc etc!

Got it all up to scratch now hopefully which is why I wanted a tach on it to make sure it was running at the right revs and then that confused the issue again!

Hopefully will have a good little sucker now when its all connected up - seems to be heating the water well and I've done a descale and changed all the oils. If its all OK I am going to convert the engine to run on LPG - doesn't cost a lot and soon get ya money back