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rob[aut]

4rt 2017 weak engine or high idle

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Hello all,

I bought a new 4rt european bike in feb already derestricted from the dealer.

I like it really as it is my first 4st trials bike.

A month or so ago a long time montesa driver told me, the idle was too high and he lowered it.

The next time I drove it (week later or so) I wanted to drive a step down but it was too high and the engine protection plate had contact with a big stone and stopped my bike while I was still moving forward :-D

The bike just fell to the side so not a big deal.

But afterwards I had to kick about four or five times and it didn't run well and even sometimes stalled at low revs while driving. I believe it also has a louder and deeper sound now.

As I had 15hrs on the bike I changed gear and motoroil, the airfilter and the spark. I removed the cable to the (small) lightmask as it was defect because once before the bike fell down in my garage (due to that ... side stand) and I saw a cable that leads to the o2 sensor not plugged in anywhere and I couldn't see any plug where it could go in... I was told, it isn't supposed to be connected anywhere in a derestricted bike

Everything went well and the bike starts at the second kick but I have to raise the idle (my hourmeter shows about 1800 rpm but I don't trust him ;-) ) too high or the bike doesn't rev up as it should and it is much too weak.

Please see 

 

Has anyone any idea what the problem could be?

Edited by rob[aut]
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5 hours ago, rob[aut] said:

That sounds too fast. 

Does the bike pop and bang? If yes you may have moved the exhaust causing a leak. 

If not check the throttle body hasn't moved and now got an air leak around the inlet rubber. 

 

5 hours ago, rob[aut] said:

 

 

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Thanks, I'll check both of your suggestions because at idle it does some kind of "blob"  (not too loud) every three or four seconds.

At first I'll remove the whole exhaust and fasten it again.

Thanks so far B)

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Your tick over sounds very fast, your tachometer/hourmeter is not correct, this maybe because the signal wire from the tachometer is too long and in contact with the fuel tank

Here are the instructions for de-restricting the 4rt, I suggest that you check that the dealer has made all the changes needed, especially removing the green/white wire from the connector and any restrictions in the throttle body and airfilter.

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Thanks @ourian and @fantic303.

I'll check that but I have 16hrs on the bike now and for the first 15 hrs the bike ran great. So the dealer derestricted the bike completely I think  :(

Edited by rob[aut]

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15 hours ago, rob[aut] said:

Thanks, I'll check both of your suggestions because at idle it does some kind of "blob"  (not too loud) every three or four seconds.

At first I'll remove the whole exhaust and fasten it again.

Thanks so far B)

Try fitting the hour meter correctly to get a more accurate reading too.

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If your problem started after a fall, chances are you damaged something to cause the problem. Check all connections, look for damaged/crushed wiring.  Re-seal the exhaust to eliminate that, same with throttle body, reduce tickover till it sounds correct.

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the rpm meter has gone wonky. the first thing that has to be corrected is the setup of the meter for correct operation, that is essential. the 4rt has to be very close to 1800 rpms to operate correctly. scrutinize the meter to see if the button was pushed during its fall and changed the settings/ I think its reading half scale right now. 

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Looking at that video either the bike has been set up with far far too much slack in the cable or something is causing the throttle mechanism not to bottom out on the stop thus resulting in the excessively high tick over and concomitant slack in the cable compared to what you had before. Too high a tickover would also explain the poor starting. 

Edited by 2stroke4stroke

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On 11.9.2018 at 2:02 PM, 2stroke4stroke said:

Looking at that video either the bike has been set up with far far too much slack in the cable or something is causing the throttle mechanism not to bottom out on the stop thus resulting in the excessively high tick over and concomitant slack in the cable compared to what you had before. Too high a tickover would also explain the poor starting. 

The bike had a high idle because I set it so high to get some power when reving up. 

Meanwhile I de- and remounted the whole exhaust and it seems to run ok by now.

I'll keep u informed :-)

Edited by rob[aut]
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The idle is WAY to high. Check the throttle twist grip. It may have been moved or damaged in the fall.

Edited by martin belair

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