Just put a new cam chain and rings in the 4RT because I thought being 8 years old it was about due. I put the engine, exhaust, injector and throttle body back on the frame but not the air box. I thought it'd be a good idea to try starting it before I got much further. I kicked it over several times with it almost starting but not actually jumping into life.

Is the 4RT "clever" enough to know the air box is missing so not start?

No it's not that clever . I bought a PTB for mine and when fitted the bike wouldn't start , Just out of interest I plugged the old standard unit in without actually fitting it and the bike started and idled fine .

 

Agreed, should start fine with the air box off, you might just need some slight adjustments on the idle screw or maybe some tension on the throttle?

I bet it's something small.

They won't start wiith a fresh oiled filters so it knows something!!

Check fuel pump plug I've thought I've plugged mine in the past only to find it's not in correctly. They can be a bit of a fiddle when putting tank on.

We are assuming all your timing marks are back ok?

Good luck

A fresh oiled filter affects the air volume and they have a mass airflow type check (don't' remember Montesa/Honda the calls it) so yes that would/could affect it.  They normally don't have an O2 unless its setup for the street so that's not likely the issue...

 

Maybe the TB is a bit dirty and not getting a good ready on the air volume measurement? 

Edited November 18, 20169 yr by jonnyc21

if the timing is ok try opening up the idle on the throttle body to 2 1/2 - 3 turns...My son turned our bikes idle down when we first got it without me knowing....took a month to get it going again!.....thanks again to Alan Bird @ Feetuptrials!!

Thanks for the suggestions.

I know that the timing is ok because I put mostly back together then wasn't confident I'd set the timing right so it was all out of the frame again.

To be honest I was struggling to get it going last night just before I was packing up so haven't done any fault finding. I was chewing it over in bed when I thought about posting the question. Looks like I'll be having a careful look at it tomorrow.

I'll let you know how it goes.

I've got it started now.

 

Checked all of the electrical connections, which were ok. So I adjusted the the tick over but 1/4 of a turn and it started ok. Obviously, putting in cam chain and rings must have mede it need just a touch more tick over.