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gaz12349

4rt engine work

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Have any 4rt owners done any internal engine work on the 4rt? Reason I ask, I've got a 2005 4rt (first batch off the production line frame number low 900s) and I have no history of any internal engine work done. In my ownership I've followed the book and replaced the oils and filter every 15 hours using the recommended oils. The book says the piston is to be changed every year however this could be the original piston for all I know. The bike runs great and pulls well. Is it worth the rather large expensive of rebuilding it? I'm not concerned about the labour as I'd carry out the work myself however the parts add up to quite a lot.

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Exactly. A pal had an '05 which he sold at 12 years old still with the original plug in it and still running like a watch. Worth checking the valve clearances but I'd go no further if there's no symptoms.

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2 hours ago, gasserguy said:

If it ain't broke, don't fix it !!!

 

It seems to have a very very mild knock on idle. I can't locate where it is. Doesn't sound like the valve clearances however I don't adjust them as often as I should. Other than that the engine performs great. Plenty of power for me.

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2 hours ago, gaz12349 said:

It seems to have a very very mild knock on idle. I can't locate where it is. Doesn't sound like the valve clearances however I don't adjust them as often as I should. Other than that the engine performs great. Plenty of power for me.

I would check the timing chain tensioner, that's the most common cause of small knock on the 4RT's if I recall correctly.  

As for maintenance on my 07 4RT, I haven't ever needed to change anything on it but oil/filter changes, clean the air filter (replaced a couple because of use).  I do swap the plug out every year or two but probably could get away longer change cycles.  

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19 hours ago, jonnyc21 said:

I would check the timing chain tensioner, that's the most common cause of small knock on the 4RT's if I recall correctly.  

As for maintenance on my 07 4RT, I haven't ever needed to change anything on it but oil/filter changes, clean the air filter (replaced a couple because of use).  I do swap the plug out every year or two but probably could get away longer change cycles.  

Thanks. Just had a look at some of the other posts regarding the timing chain tensioner. Certainly something I'm going to check. It would be nice to replace it with a manual one and cure the mild knock. I change the oils and filter every 15 hours. However using the ELF HTX 740 in the gearbox is getting expensive! 

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7 hours ago, gaz12349 said:

Thanks. Just had a look at some of the other posts regarding the timing chain tensioner. Certainly something I'm going to check. It would be nice to replace it with a manual one and cure the mild knock. I change the oils and filter every 15 hours. However using the ELF HTX 740 in the gearbox is getting expensive! 

Yes, the HTX is a bit expensive.  I know a few people that have recently changed to the "NILS CLUTCH TRIAL" oil and are having great luck with it.  The specs of that oil are very close to the same as the ELF oil so I am intending to give it a go myself.  I don't know the cost difference but it might be worth checking into?  Good luck on the

 

Specs for comparison. 

ELF 40°C 21.4 100°C 7.0
NILS 40°C 24.7 100°C 7.5

 

Also, take this as you will, I change my ELF oil every 2 oil changes (30 hrs) and can't tell a difference in performance on the clutch.  I once went to 65 hours on my 07 4RT so I could see where the tipping over point on clutch feel was and found that it only started to feel a bit off at the 60 hour mark and even then only just.  I keep it at the 30 hours on my 300 RR but after then 65 hour test I wouldn't have a big issue going over a bit if needed. 

Edit: looking like it might be as much as about half the price here in the US... defiantly worth a go for that in my mind. 

Edited by jonnyc21
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They're pretty good to split the engine, it's a Honda, everything fits where it's supposed too and working from the manual makes it a doddle. I've done a couple of new con rods after bikes have been drowned and they're fairly straight forward. (One was mine in the 2019 Scott) 

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On 11/11/2020 at 11:21 PM, jrsunt said:

They're pretty good to split the engine, it's a Honda, everything fits where it's supposed too and working from the manual makes it a doddle. I've done a couple of new con rods after bikes have been drowned and they're fairly straight forward. (One was mine in the 2019 Scott) 

Just in the middle of splitting my 06 repsol that has a mild knock. Looking to replace main bearings seals and gaskets and see what the piston is like and hoping the crank is ok.  I’ve had the bike from new and it’s on its original piston, it’s done 4 SSDTs but been cared for. I’m reasonably good on mechanics and done cam belts etc ... is there any pit falls with the 4 rt I should be aware of ? I’ve got clutch basket and flywheel off as we speak. Any advice appreciated......other than take it to a dealer !! 

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My 2012 had done 4 ssdt's, 6 Scotts and was thrashed within an inch of it's life everywhere it went. I was going to put a piston and get the barrel done when I sold it, but when I stripped it down everything was perfect and measured to spec, so it went back together with new gaskets and rings only.

I would guess that most of your internals will be ok, the only damage usually occurs from water. My 18 was drowned in the 2019 scott about 2 mins from the start. The bike knocked its tits off for the rest of the day. Upon stripping it down, the woodruff key had folded itself in half and stretched both ends of the con rod resulting in a knock that was noticeable throughout the rev range. 

If you split the crank, just make sure you measure and mark everything up. I made some plates  up to help pressing everything back together so it couldn't be over pressed. The con rod is only available as a complete crank assembly, but the rod is a crf250 rod which are available everywhere.

Just follow the manual and it's pretty straight forward, I don't think there is anything untoward. It's a little fiddly getting the cam chain and cam back on in the correct place but other wise ok.

 

C03CC7E1-6D45-4AEE-9569-E07D617C8408.jpg

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