2018 RMZ 450 Technical Help Hard to Start

NialOx
Posts
44
Joined
1/15/2021
Location
GB
Hello all,

I've got a 2018 RMZ450. It's on about 55hrs with a top and bottom engine rebuild at 30hr.

Cold it starts great and runs great when warm. However after the bike has warmed up it's nearly impossible to start again, I always eventually get it going without a bump start but we are talking 20-30 kicks.

Does anyone know the specs for the valve clearances?

I can't find a service manual for this age RMZ anywhere at all. Ideally id like to do a compression test but without the manual I can't find the figures.

Or does anyone else have any other tips?

Possibly the coolant temp sensor etc causing it to run to rich when starting hot?

As I say when it get's going it runs brilliantly.

Cheers
|
Sandusky26
Posts
3134
Joined
7/28/2021
Location
Eastern, NC US
3/8/2022 12:56am
NialOx wrote:
Hello all, I've got a 2018 RMZ450. It's on about 55hrs with a top and bottom engine rebuild at 30hr. Cold it starts great and runs...
Hello all,

I've got a 2018 RMZ450. It's on about 55hrs with a top and bottom engine rebuild at 30hr.

Cold it starts great and runs great when warm. However after the bike has warmed up it's nearly impossible to start again, I always eventually get it going without a bump start but we are talking 20-30 kicks.

Does anyone know the specs for the valve clearances?

I can't find a service manual for this age RMZ anywhere at all. Ideally id like to do a compression test but without the manual I can't find the figures.

Or does anyone else have any other tips?

Possibly the coolant temp sensor etc causing it to run to rich when starting hot?

As I say when it get's going it runs brilliantly.

Cheers
.004-.006 intake and .007-.009.

I have a 20 RMZ, my valves went at around 60 hours and would be hard to start cold. I would sometimes have to use the choke to get it started once it was warm.
1
NialOx
Posts
44
Joined
1/15/2021
Location
GB
3/8/2022 3:09am
Nice one,

Mine seems to start fine cold though. Strange
Sandusky26
Posts
3134
Joined
7/28/2021
Location
Eastern, NC US
3/8/2022 3:15am
NialOx wrote:
Nice one,

Mine seems to start fine cold though. Strange
You can feel the loss of compression when the valves start to move. You could try cleaning the fuel filter/sock in the fuel tank. I would check the valve clearance just to be sure.
1
NialOx
Posts
44
Joined
1/15/2021
Location
GB
3/8/2022 3:19am
NialOx wrote:
Nice one,

Mine seems to start fine cold though. Strange
Sandusky26 wrote:
You can feel the loss of compression when the valves start to move. You could try cleaning the fuel filter/sock in the fuel tank. I would...
You can feel the loss of compression when the valves start to move. You could try cleaning the fuel filter/sock in the fuel tank. I would check the valve clearance just to be sure.
You might be right then.

I'm a pretty big guy. And although I've never found a bike hard to kick I have to say when warm it did feel especially easy.

The Shop

NialOx
Posts
44
Joined
1/15/2021
Location
GB
3/9/2022 12:40am
Update.

Tore into the bike.

Exhaust valves are in spec but only just. 0.15 and 0.17

Intake valves are one in just and one way out. 0.11 and the other is less than 0.05 as that's the smallest gauge I have.

Good news is the shims installed still have some meat to them at 2.7/2.75 exhaust and 2.3/2.35 intake.

I've ordered some shims to hopefully take me to the upper end of clearances.

1
RMZguy420
Posts
3
Joined
6/4/2024
Location
De Te, ME US
6/4/2024 11:09pm
NialOx wrote:
Hello all, I've got a 2018 RMZ450. It's on about 55hrs with a top and bottom engine rebuild at 30hr. Cold it starts great and runs...
Hello all,

I've got a 2018 RMZ450. It's on about 55hrs with a top and bottom engine rebuild at 30hr.

Cold it starts great and runs great when warm. However after the bike has warmed up it's nearly impossible to start again, I always eventually get it going without a bump start but we are talking 20-30 kicks.

Does anyone know the specs for the valve clearances?

I can't find a service manual for this age RMZ anywhere at all. Ideally id like to do a compression test but without the manual I can't find the figures.

Or does anyone else have any other tips?

Possibly the coolant temp sensor etc causing it to run to rich when starting hot?

As I say when it get's going it runs brilliantly.

Cheers

U ever find the problem I have a 22 doing same thing

RMZguy420
Posts
3
Joined
6/4/2024
Location
De Te, ME US
6/4/2024 11:11pm
NialOx wrote:
Hello all, I've got a 2018 RMZ450. It's on about 55hrs with a top and bottom engine rebuild at 30hr. Cold it starts great and runs...
Hello all,

I've got a 2018 RMZ450. It's on about 55hrs with a top and bottom engine rebuild at 30hr.

Cold it starts great and runs great when warm. However after the bike has warmed up it's nearly impossible to start again, I always eventually get it going without a bump start but we are talking 20-30 kicks.

Does anyone know the specs for the valve clearances?

I can't find a service manual for this age RMZ anywhere at all. Ideally id like to do a compression test but without the manual I can't find the figures.

Or does anyone else have any other tips?

Possibly the coolant temp sensor etc causing it to run to rich when starting hot?

As I say when it get's going it runs brilliantly.

Cheers

Having same problem with my 22 rmz 450 with only 37hrs on it 

seth505
Posts
9565
Joined
4/1/2008
Location
SD, CA US
6/5/2024 7:28am
RMZguy420 wrote:

Having same problem with my 22 rmz 450 with only 37hrs on it 

Have you checked valve clearance yet?

Post a reply to: 2018 RMZ 450 Technical Help Hard to Start

The Latest