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1986 radian 600


Rod P
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Hey there, I'm new to this site so please forgive me if I screw up this posting. I have just purchased a 1986 radian with aprox 27,000 miles on it, it runs great and pulls hard but it has a knocking sound coming from the engine when at idle when cold. once it warms up and is at proper idle speed the knock goes away. You can aslo make the sound go away when cold if you give it just a little gas to bring the idle up. Does anybody have any ideas about the cause of this noise, I was thinking maybe timing chain slap or maybe low oil pressure, although the oil light does not come on? any help would be greatly appreciated.

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Possible valve clearances and tappets need attention. They should be done at max 24k intervals, or three years (at least that is what I personally recommend).

Do you have any history to tell you if either have been done at all?

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Hey there, I'm new to this site so please forgive me if I screw up this posting. I have just purchased a 1986 radian with aprox 27,000 miles on it, it runs great and pulls hard but it has a knocking sound coming from the engine when at idle when cold. once it warms up and is at proper idle speed the knock goes away. You can aslo make the sound go away when cold if you give it just a little gas to bring the idle up. Does anybody have any ideas about the cause of this noise, I was thinking maybe timing chain slap or maybe low oil pressure, although the oil light does not come on? any help would be greatly appreciated.

Hi Rod,

At what engine speed does your YX600 knock <1k or 3k ? With the choke on the bike is normally at fast idle ,3k or there abouts, and decreases when the choke is turned off. The correct idle speed, when warm is about 1.1k.

The oil light is level rather than pressure so if the bikes has pressure problems the light wont come on as long as there is enough oil in the engine, but one thing to take note of the light may come on under high engine speed & up hill (it will flicker a bit) this is normal.

Valve clearances on the YX do have a shorter service time than water cooled varients and tended to tighten up rather than loosen, good practice would be to check the clearances, adjust the cam chain, balance the carbs & adjust the mix screws, this will normally remove most knocks from the engine.

Regards Jim

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Hi Rod,

At what engine speed does your YX600 knock <1k or 3k ? With the choke on the bike is normally at fast idle ,3k or there abouts, and decreases when the choke is turned off. The correct idle speed, when warm is about 1.1k.

The oil light is level rather than pressure so if the bikes has pressure problems the light wont come on as long as there is enough oil in the engine, but one thing to take note of the light may come on under high engine speed & up hill (it will flicker a bit) this is normal.

Valve clearances on the YX do have a shorter service time than water cooled varients and tended to tighten up rather than loosen, good practice would be to check the clearances, adjust the cam chain, balance the carbs & adjust the mix screws, this will normally remove most knocks from the engine.

Regards Jim

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Hi, thanks for the advice. I do not have any service records from the guy I bought it from. I will check to see for sure but I believe it knocks at anything under about 1300 rpms when cold. I will let you know if the adjustments you suggested work.

Thanks again

Rod

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Hi, thanks for the advice. I do not have any service records from the guy I bought it from. I will check to see for sure but I believe it knocks at anything under about 1300 rpms when cold. I will let you know if the adjustments you suggested work.

Thanks again

Rod

Hi Rod,

in that case the motor needs the carbs adjusting .. balance & mixture... I guess the noise is only there without the bike under load (tick over in N) when the bike is running it's fine ? try the following :- allow the engine to warm up and idle then switch the lights on ... if the idle alters you have a defo carb problem (balance/mix). If the idle does alter and the knock remains that will pin point the problem to mixture, to a degree I have added this coment to loads of posts and from the replies no one thinks this is true, but as a chalenge to any one bring me a XJ550/600/YX600/XJ650/750/900 with the knock at idle problem & I'll fix it for free !

Regards Jim

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If the idle does alter and the knock remains that will pin point the problem to mixture, to a degree I have added this coment to loads of posts and from the replies no one thinks this is true

I can see what you are saying here and I do agree with most of what you have said.

However, don't overlook the fact that any carbed bike will suffer a momentary dip in rpm at idle when accessories, such as lights, are turned on.

This is due to the extra demand being put on the electrical system and in turn, the charging system, which is powered by the 'dyno' on the engine. Carbed bikes take a moment or two to recover from this extra load demand.

FI engines are better equiped to cope with this, apart from the fact that most modern FI bikes have headlights on permanently anyway.

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I can see what you are saying here and I do agree with most of what you have said.

However, don't overlook the fact that any carbed bike will suffer a momentary dip in rpm at idle when accessories, such as lights, are turned on.

This is due to the extra demand being put on the electrical system and in turn, the charging system, which is powered by the 'dyno' on the engine. Carbed bikes take a moment or two to recover from this extra load demand.

FI engines are better equiped to cope with this, apart from the fact that most modern FI bikes have headlights on permanently anyway.

Hi,

There is a difference between a slight dip 30/40 rpm and where I was coming from nearer a couple of hundred rpm from the training I was given this would give you a carb fault (in this case the knock from the motor was a diagnostic bonus). I know nothing of FI bikes as I have never worked on one that had a fault with the FI, But I would guess that the inbuilt software in a FI system would 'fault' efi light on or tacho going into fault mode) if a problem occured with carbed motors you had to work out what was amiss, with the early XJ/YX/FZ motors they suffered badley with the 'knock' there has been loadsa times the (then 17 year old who had passed the test) came in with an XJ series motor with about 4,000 miles on thinking it was knackered (shouting warranty) had to be gentley told you need to have your carbs done !

Regards Jim

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Hey there, I'm new to this site so please forgive me if I screw up this posting. I have just purchased a 1986 radian with aprox 27,000 miles on it, it runs great and pulls hard but it has a knocking sound coming from the engine when at idle when cold. once it warms up and is at proper idle speed the knock goes away. You can aslo make the sound go away when cold if you give it just a little gas to bring the idle up. Does anybody have any ideas about the cause of this noise, I was thinking maybe timing chain slap or maybe low oil pressure, although the oil light does not come on? any help would be greatly appreciated.

hi ,I have one of these machines and I suspect its the old clutch rattle,does it cease when the clutch is engadge similar to R1 models as a good friend sats

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hi ,I have one of these machines and I suspect its the old clutch rattle,does it cease when the clutch is engadge similar to R1 models as a good friend sats

Hi Piston Bloke

Whats the old clutch rattle ? I'd love to know as all this bike suffered from i.e the series Xj550/600 & YX was bad carburation. If you applied the clutch at idle there is a chance the noise would disappear, but where was the root of the problem ?? release bearing perhaps .... or perhaps the primary drive chain or could it be the oil gallery from the crankshaft to genny shaft to clutch blocked ? I would guess by the time the R1 was born the latter would have been sorted .. in fact by the time the motor was in the FZ600 frame these were sorted. So if you have a knock at idle on a pre FI R1 it will be the same problem that I mentioned in earlier posts.

Regards Jim

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  • 11 months later...

Hey there, I'm new to this site so please forgive me if I screw up this posting. I have just purchased a 1986 radian with aprox 27,000 miles on it, it runs great and pulls hard but it has a knocking sound coming from the engine when at idle when cold. once it warms up and is at proper idle speed the knock goes away. You can aslo make the sound go away when cold if you give it just a little gas to bring the idle up. Does anybody have any ideas about the cause of this noise, I was thinking maybe timing chain slap or maybe low oil pressure, although the oil light does not come on? any help would be greatly appreciated.

I also have an 86 Radian with 15,000 miles. I am also having the same knocking sound problem EXACTLY as you described, when its cold, and under 1300 rpm. I'm going to take it in and have the valves looked at as well as havee the carbs synced. ill let you know what happends.

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  • 11 months later...

I have a 1988 Radian with 18,000 miles on it. It sat for 2 years, and had the same fuel in it. It ran good 2 years ago, except stalled sometimes at idle. a little choke, or a little throttle fixed this. Last year, the bike was "Sold" and when the new owner picked it up, it stalled 3 miles away. the bike sat for a while , then re-fired and made it back to the home it came from. The seller of the bike replaces the stator and some other stuff, the new owner returned to get the bike again, and the same result. the bike then sat for almot a year... it still had the same gas in it. I got the bike for free and here I am. The battery was charged, the tank and carb bowls were drained, and it stunk of varnish.. the bike would idle for a few minutes though (Don't ask me what it was running on, I dont know. it still smells like the old fuel in it.) I filled the tank with premium fuel, with sea foam added to it, and now it idles with the choke on. even after it warms up (It now runs long enough to warm up) it stalls immediately if the choke is turned off, or if any throttle is applied. I have only had a few ounces of fuel run through it, Running the whole tank will take days... I am prepared to do this if necessary. It idles around 2,000 RPM with the choke on. If i throttle the bike wide open right when it fires it winds up to 4,000 RPM and stays there...

Please help!

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