hi there guys,can any one help me out there as i have just finished restoring my 83 xr350 ,but am now wanting to change the swing arm to one off a 85 xr350 which is bigger and is alloy , what i need to know is can i bolt this swing arm straight on without changing the drum brake set up or do i have to go to the disk set up as all my brakes are brand new , also any other advise or things that need to be changed would be appreciated,as i have heard people have done it before thanks .
xr350 swingarm change.
- Thread starter fletcher
- Start date
- Thread starter
- #7
76gmc1500 if your still there or anyone who may help ,when i swap the swing arm over can i still use my original shocky,spring and linkage or do i have to use the ones ,off the 85 model and also will i have to change the brake rod to a longer one and the chain or can i use mine, as they are all new .
The cases for an 85 and 83-84 appear to be different part numbers as do the swing arm pivot bolts and link arms. This doesn't necessarily mean the parts wont fit, but it doesn't mean they will. It may be a worthwhile experiment if the price is right. www.servicehonda.com has all of the microfilms and part numbers.
dirt bike dave
Sponsoring Member
- May 3, 2000
- 5,348
- 3
The '85 motor was changed quite a bit, so it would not surprise me if the swingarm needed to be modified to fit the '83 - '84.
FWIW, a much cheaper and easier alternative than an '85 swingarm would be to add a couple of links to the chain and run the wheel all the way back as far as it will go in the existing swingarm. You will gain an 1" or so of wheelbase and keep the bike original.
My buddy had an '84 and we had many good times with that bike. The extra wheel base will help with hillclimbs. The bike has a good hill climbing motor, but the high center of gravity and short wheelbase make it want to loop out.
FWIW, a much cheaper and easier alternative than an '85 swingarm would be to add a couple of links to the chain and run the wheel all the way back as far as it will go in the existing swingarm. You will gain an 1" or so of wheelbase and keep the bike original.
My buddy had an '84 and we had many good times with that bike. The extra wheel base will help with hillclimbs. The bike has a good hill climbing motor, but the high center of gravity and short wheelbase make it want to loop out.
- Thread starter
- #17
while were talking , does any one out there know the measurments for oil for each of the front forks on my 83 xr350 thanks, and do i unscew the plug underneath the bottom of the fork to empty or the little screw on the side at the bottom , and when i fill do i just undo the top plug where the valve fits in .
dirt bike dave
Sponsoring Member
- May 3, 2000
- 5,348
- 3
The little screw on the side at the bottom should be used to drain the oil. The plug underneath holds the damping rod assembly. You will not need to remove the damping rod to change the oil.
Rather than refill by using a specified volume of oil, it is best to measure how high the oil level is. Loosen the fork tube pinch bolts on the upper triple clamp and then remove the large cap. Remove the springs, and collapse the fork all the way.
As a general rule on old style forks, fill until the oil is 4" from the top of the fork tube with the forks collapsed and the springs removed. This should get you in the ballpark.
Oil level primarily effects bottoming resistance and stiffness at the last part of the travel. Higher oil level will make it stiffer at the end. 1/2" of change in the oil level either way will make a big difference.
Actually, before you drain your oil you might want to measure the current level (remove the springs and collapse the fork first). If you like how they rode before, refill to the same level. If they bottomed too easily, raise the oil level.
Heavier oil will slow the fork rebound. Lighter oil will make it rebound faster. But you probably should stick with the weight that Honda recommends.
My guess is you will probably need around 1.5 pints per leg, but I would be more concerned about oil level than putting in the exact amount of ml you find in some manual.
Rather than refill by using a specified volume of oil, it is best to measure how high the oil level is. Loosen the fork tube pinch bolts on the upper triple clamp and then remove the large cap. Remove the springs, and collapse the fork all the way.
As a general rule on old style forks, fill until the oil is 4" from the top of the fork tube with the forks collapsed and the springs removed. This should get you in the ballpark.
Oil level primarily effects bottoming resistance and stiffness at the last part of the travel. Higher oil level will make it stiffer at the end. 1/2" of change in the oil level either way will make a big difference.
Actually, before you drain your oil you might want to measure the current level (remove the springs and collapse the fork first). If you like how they rode before, refill to the same level. If they bottomed too easily, raise the oil level.
Heavier oil will slow the fork rebound. Lighter oil will make it rebound faster. But you probably should stick with the weight that Honda recommends.
My guess is you will probably need around 1.5 pints per leg, but I would be more concerned about oil level than putting in the exact amount of ml you find in some manual.
- Thread starter
- #20
i done what you said dirt bike dave , pulled the springs out and dropped the forks down, drained oil out and was only about half a quart in each so i filled the forks up with new oil to 4 inch from top of fork pipes and put them back together , they both took 1and a haif quarts for both , when i took bike for a ride they seem to have no or very little pressure at all , is there a psi air level that has to be pumped into them or should they hold a fair bit of pressure without air , i used motul medium 10w oil , will the oil level be to low in the forks you think , you said they would take 1.5 pints each but the oil bottles here in australia are measured 1litre or 1.05 quart and both of the forks took 1.5 quarts or just under 1.5 litres to fill both ???.
dirt bike dave
Sponsoring Member
- May 3, 2000
- 5,348
- 3
When you measured the 4" from the top with the new oil in, was that with the forks compressed all the way?
Also, you should probably slowly stroke the fork a few times with the springs out and the caps off so that any air bubbles rise to the top and so that the oil gets everywhere it needs to go. Not doing this may have resulted in too little oil.
Is there any pre-load on the fork springs? About 10mm should work well. There should already be pre-load spacers in the forks. These fit between the bottom of the cap and the top of the fork spring. If your bike did not have them in, you may need to make some. Be sure to account for thickness of the fork cap, though.
While you can use the air valves to stiffen the fork, this is not usually desireable. It makes the forks less compliant on the initial part of the travel. It is usually best to get the correct spring for your weight, and then fine tune with oil level, spring pre-load and oil weight.
Also, you should probably slowly stroke the fork a few times with the springs out and the caps off so that any air bubbles rise to the top and so that the oil gets everywhere it needs to go. Not doing this may have resulted in too little oil.
Is there any pre-load on the fork springs? About 10mm should work well. There should already be pre-load spacers in the forks. These fit between the bottom of the cap and the top of the fork spring. If your bike did not have them in, you may need to make some. Be sure to account for thickness of the fork cap, though.
While you can use the air valves to stiffen the fork, this is not usually desireable. It makes the forks less compliant on the initial part of the travel. It is usually best to get the correct spring for your weight, and then fine tune with oil level, spring pre-load and oil weight.
- Thread starter
- #22
yer man the springs were compressed all the way up as they are still on the bike when i done them and all the weight of the bike where on them, i slowly poured oil in so that it would fill all the fork up and yer about 10mm of preload is present, and spacers are there to , how will i go if i jack the front end up so the wheel dosnt touch and undo top screws and pull out springs and try a bit more oil in both then reinsert the springs and caps and try or should i compress forks up again and check level.
dirt bike dave
Sponsoring Member
- May 3, 2000
- 5,348
- 3
fletcher said:
That's what I would do. I think I would meaure first and see if you are still at 4" (or approx. 100 mm) oil height at full compression with springs removed and forks compresssed. If not, raise oil to 4". If you are already at 4", add enough oil to raise to 3.5" from the top.
It might be useful to know how much oil it takes to raise the level 1/2" (12.7mm), so pour from a pre-measured amount. That way if you need to add or remove oil again to adjust the fork, you don't have to spend as much time measuring.
If you get too high on oil level, the forks will feel fine during the first few inches of travel, but may not be able to compress all the way when the springs are in. You probably won't run into a situation where you are losing fork travel until you are less than 3" from the top on oil level. I don't think I would go less than 2.5".
Basically, the air in the fork gets compressed as your suspension bottoms, and helps stiffen up that last part of your fork travel. By having more oil, you have less room for the air to compress into at full compression. This makes the fork stiffer as it nears full compression. If you have the oil too high, there is no room for the air to compress into and the fork loses travel.
You basically want the oil level low enough so that you still use full travel on big hits, but high enough so that your fork is stiff enough on the big hits. This takes some fine tuning, but once you get it set, the fork should work better for you.
On many of the older bikes, the factories did not put in enough oil (my old '84 KDX200 was more than 6" from the top). So if you do find a shop manual that tells you how many cc of oil you need, you would still need to fine tune it to work best for you.
Last edited:
Ol'89r
LIFETIME SPONSOR
- Jan 27, 2000
- 6,958
- 45
dirt bike dave said:
fletcher.
The factory manual states, 553 cc's or 18.7 ounces in each fork leg.
Standard oil level, Maximum. 152 mm - 5.98 in. from top.
Minimum oil level. 112 mm - 4.41 in. from top.
Measured with forks completely compressed and springs removed.
Recommended fluid. ATF.
These are the factory recommended baselines, but like dirt bike dave said, they can be modified to suit your weight and riding style.
When I used the stock forks on my 350, I found the ATF to be too light and had to use a heavier fork oil to keep them from bottoming.
- Thread starter
- #25
thanks dirt bike dave and ol 89r , ill try it again and see how i go , like i said the oil im using is 10w so should stand up alright , also can you guys tell me what air pressure to put into forks when finished or if any thanks.(and i read a reply of yours ol89r about some simple things to improve performance of these bikes and you said to replace the resistor in the plug cap with a lenght of rod , what sort of metal would you use and what lenght will it have to be meaning do you have to drill a hole in the rod to sit over the spark plug tip or will just contact of both plug and rod be needed).
