1986 510 4stroke twin shock project phase #2

[ruwfo]

The frame bosses on the 83 frame, where different length, but the kink in the frame is better than have way up the front tube. After centering
the engine by cutting & spacing out the bosses, the pipes clear the frame fine. The original 86 frame & the 82 frame both had equal length
bosses & the motor was center in the 86 frame, so i just recreated what Husky did. Not sure why the 83 WR frame has a kink or why the
motor isn't center. All my other Huskys have the motor's centered in the frame (80 390CR, 83 250XC, 83 430CR, 84 500CR & the 86 510),
so i doesn't make sense why this WR is offset, but it is.

 

[fran...k.]

I have assumed the engine was in the center, those little through tubes stayed in the same virtual place and the kink of the tube moved the bottom portion of the front frame piece.

Most likely you have engines with the 12 mm swingarm pivot bolt where you have seen denting in the rear inserts from the hard steel piece the bearings ride on which kind of resembles a piston wristpin. If it was me and I didn't choose to make new rear engine inserts I would remove them and weld in the sleeve with some filler rod not of super soft variety and clean up the end in a lathe or some other way before re installing. A piece of copper in the hole will preserve it during this process.

Fran

 

[ruwfo]

Well, as most projects go, mine has changed gears a few times, from reverse to forward. As luck would have it, while modifying the 1983 430WR chassis to fit my 86 510 motor, i came across an original twin shock 510 frame. So i swapped the motor from my modified frame to the original one. Doing this eased the build process/time factor , by not having to make mid pipe exhaust & body side panel mounts.
As it was only a frame, i'm still using these early model parts: 1983 XC swingarm & rear brakes components, 1981 CR front end, so far.
I had already purchased a set of early model pipes, as the front pipes differ from the single shock ones because they curve around the shocks.

Ok, nothing earth shattering happened while reassembling of the motor, exhaust, front end assy. I had already gotten the 510 original shock length & swingarm dims from the guy who sold me the frame & what i already had, matched. So those parts where put on with No drama, except the swingarm pivot bolts on the single shock bikes are larger in diameter then the twin shocker are, 14mm vs 12mm . I found McMaster
sells bearing sleeves, which match those sizes exact , so i blue loctited some in the rear motor engine case holes. Swingarm, shocks etc mounted up fine, along with the exhaust system.

As i think was mentioned early in this thread, the original 510 frame Does not have a kink in the front frame tube, but does have the motor centered in the frame. See attached picture

 

[ruwfo]

I original thought of using a the 17" rear, because i had one off the 1981 CR rolling chassis i got the front end from. But as it looks like either the hub offset is different or the counter shaft sprocket is offset different from 2 stroke to 4 stroke. Whatever it is, i put the 1986 18" wheel on, using
a dual shock bike axle, a 82-84 XC/WR rear brake hub & the left side axle spacer that was on the 86 wheel & everything lined up correctly. One thing i did notice though is that although the brake shoes are the same size, the backing plate is slightly smaller in diameter then the wheel area it's suppose to cover, leaving a very small gap. After looking at some pictures of the 85 WR/XC dual shock only bikes, the backing plate looks about a 1/8" larger in diameter then the older model ones. I guess i've got to get another backing plate, to add to the collection LOL.

 

[husqyhamm]

I run a 86 500TC barrel, piston(90mm) and head on one of my 84TEs, while the whole bottom end is original. As said angle on inlet port flange is different and when I have time by next week I'll photograph and post my simple yet very effective solution which also improves performance, have patience plse. Also the cooling fins on the 86 are quite a bit bigger which here in Africa is an absolute bonus and the setup of choice.

When you swap Singleshock bottom ends into Twinshock frames:
Swingarm bolt on 83-84 twin is 12mm and on single is 14mm and way shorter than the 12mm bolt. Some of the earlier frames are even 10mm bolts which is an absolut no-no with 510 torque.
I machine swingarm bolts from axle steel (old fwd sideshafts) and for the bushes you go to a quad workshop and find yoursef a handfull of good used 20mm gudgeon pins, I think they came off a 400 Suzuki. To bore (almost ream) the gudgeon pins if need be, you put the bush in a lathe and mount a high quality 14mm concrete (yes) drillbit, which comes with tungsten tips and gets the job done for bushes and also the frame, together with Tapmatic. Obviously afterwards you machine the bush to correct length too.

Love that 84TE, handles way better than any of my singleshockers (including a real trick 86TX).
Its stupid fast yes.
In a drag it gives new 300 2Ts a solid hiding (oops), just runs with 450s, and topspeed its adios dudes. Very few mod bikes can actually hurl along at 100mph+ as these comfortably can with a 14/48 sprocket setup.

Good luck, its a worthy project, and if you can get the frame headstock to 28,5 deg, even sweeter for taking the inside and flatout sideways through turns.

 

[husqyhamm]

Ps, just read the part where you obtained original TE frame, xcellent.
Just ensure the bearing sleeves go the full length through the engine casings, otherwise the righthand one will come loose, relocate towards the centre and you will experience suicidal headshake when decellerating, with damage to bolt and frame.

 

[ruwfo]

I have noticed that the 85 510's have a different swing arms then the early models (83-84), with a extra reverse facing bolt in front of the axle. I'm guess that's a design improvement Husky made to combat the deceleration torque of the engine as well?
Thanks for the tip on the swingarm pivot spacers, i'll make sure mine are long enough.

 

[SA63]

Very interesting! I am doing ruwfo's project in reverse.. building a 86 using a earlier top end with l/c bottom end, so have the reverse head problem, which i think is less of a headache as the manifold is shorter (no spacer) so look forward to mor info..
I rode a "special" -84 frame with tt 500 motor with cut down,"twin shocked" 86 alloy swingarm and I have to say on tight corners its absolutely out turns my 84 te. the frame was extended 40 mm lower to accomadate the engine and forks were probably a bit softer so extra weight + lower weight+ compressed forks = best turner. Both bikes had the forks about 20mm through the top of the triple clamp. It was nowwhere near as fast though..
So question- what is the head angle on the 84? I know my 81 maico is 28.5 and it out turns the te. I also rode a 84 500 auto and that out turns the te as well..but thats a different beast altogether..

 

[ruwfo]

Ok, more things i've learned while working on my 510 twin shock project.
1st : the front end I'm using is off a 1981 250CR 2nd: i wanted to go to the leading
link brakes of the 1983-84 & 85 (WR).
Husky T already has a great indebt look at the leading link brakes.
http://www.cafehusky.com/threads/1979-80-cr390-works-hybrid-project-passion-inspiration-action.1173/page-3#post-23079

But what i didn't realize was that the front hubs were changed along with the brake plate assemblies. So
you need to have a 1983-85 front wheel if you want to use the (leading link) brake parts. As you can
see the from the pictures left sides of the later model hubs changed & that makes them easy to spot
vs the 81-82 ones.

 

[Picklito]

AWESOME thread and build! But I'm a little confused, too. Husky DID make an air cooled 4 stroke dual shock "white bike"... so how come you're having to do so much frame fabrication? Is it because you're not using an original 4-stroke frame? I'm just curious, not criticizing.

I have several 81/82 and 83 two strokes. At first glance, the 83 frame looks like they used the same engine cradle and just tweaked the rear shock geometry for the ITC suspension design. Not so! They moved the engine forward almost an inch, and had to put that "kink" in the downtube and change the front motor mount plates and...

 

[ruwfo]

Yeap, i started with a 1986 single shock 4-stroke, & the plan was to make a dual shocker using my motor. Husky didn't make too many twin shock
510's , so i started modifying a 83 430 frame til i was lucky enough to find an original 510 frame. Actually the 430 frame is alot closer to a the 510
frame then you may think.

 

[ruwfo]

As i work on my 510 project, i always wondered why you don't see too many 510,at least i haven't ,well this maybe the reason. This from a 2/85 Cycle World, they stated "This engine first appeared in 1984 accompanied by lots of fanfare-but lots of problems, as well. Marginal ignitions, slipping clutches, quickly wearing valve guides & problems with overheating and carburetion immediately earned the Husky 4 stroke a bad reputation that prompted a factory recall."

For a small manufacture to recall all it's 4 strokes, must have been very costly

& probably along with decreased sales in general of all Husky s in the mid 80's probably lead to the company being sold?

Also noted in the article, the 1985 models got new Ignitions, bronze valve guides, stronger clutch springs, longer cylinder fins, and a 40mm carb to replace the 36mm. They (CW) remarked how light the motor is, basically 15lbs lighter then any other 500/600cc 4 stroke of the day, quite a technical feat for a small company like Husky.

More magazine 510 stuff to come.
Husky John

 

[SA63]

keep the info coming! I would really like to see a test on the 86...

 

[husqyhamm]

Gents, my bike is filthy, my arm recently fractured, thus I'll describe setting 86 engine up into 83/4 frame.

86 the rubber manifold bolts straight to the head at an angle which is square to the engine stroke for the manifold flange and bolts, giving a very short inlet tract.
83/4 head had an allu spacer between same rubber manifold and head, the angle of this party is not square to the stroke but downward thus dropping the carb lower and much longer tract. This angle for manifold and bolts obviously is machined to the head.

I took one of those 83/4 allu spacers and machined the angle onto it. The topside just clears the cut and bottomside is taken off by 10mm. Then a 4mm flange is made to match footprint of rubber manifold. Perpindicular to flange weld tube of 40mm id and some 35mm in length, the external od close to that of carb as possible. I use a rubber manifold connector, pirated off a R80G/S BMW airhead, to flushmount carb to new manifold.
Lastly your bolts require an angled washer for seating onto new flange, which I hacksawed from copper tubing.
All the above obviously gasketted and airtight.
This setup moves the 40mm DeLlorto carb backwards towards airbox by a whole 20mm above 83/4 and like 2 inches over 85/6 which was a less than blueprinted setup. You need to make a plan to actuate choke which now falls outta fingers reach.
Lengthening inlet manifold and adding 2 megaphones makes it substantially faster and more responsive than 86. Best running motor ive had yet, and xcept for the above its stock 500TC.

The 500/510 became commercially available mid 83. It was pushed into production too quick and had basic gremlins and assembly quality control issues.
Clutch slipped yes but 1mm spring spacers sorted that. The 1st 83s had 36mm squirter Dellorto, no hassles with it at higher altitudes and it ran like a bat outta hell as is. I'll rebuild one of my 83TX's with this setup for historic sake and to prove a point. 40mm Dellortos, minus accellerator pumps, came in 84 already.
The ignitions were an issue to some extent yet that was changed together with crankpin taper for what was the best at the time.
The rael bitch was nobody understood the fact that the kickstarter mechanism was that of a 240cc 2T which was already overstressed in 500 config, nevermind a 4T with substantial valvespring pressures. Its a trick kicking these things to life, especially once hot and flooded, like i recently experienced at the bottom af a ravine during a race.
All the valveguides (bar one super low hour 86 TC) ive come across needed replacement after looootsaa running.
For all the criticism its incredible how poked rings, pistons, valves, valvestems, rods can be and once going these things still smokily run the beejezuz outta all else.

Far as i care, any other 4T motor of the time and up to 6yrs later was a complete and obsolete relic by comparison.
Husky showed clearly that a 4T could run with and away from the bigbore 2Ts and started the resurgence of 4T technology.

With megaphones they still sound better that any other 4T single. Music for pistonheads with go thats still way up there.

 

[pvmx510tc]

Great thread! I'm doing the same project, but my 83 wr frame has been modified. we cut the head stock's gusset to pull the forks in to 27 degrees of rake & 4.5"of trail, then welded in new gusset. Also welded thick washers on swing arm gusset so s/w axle has more bite. Lower frame rails have additional tubing added for strenghtening. My mentor also recommended adding brace across airbox to strenghten upper shock mounts, It will make changing air filter a problem though. We also have a fix for twin leading front shoe, made a new push rod out of aluminum with left & right threads for adjustments, seems the stocker is a push rod that flexes under load. Next project is a mod. to the Ohlin shock gas tube that replaces the internal piston with a KTM bladder. If anyone is interested we can make them available with instruction for a few $

. 40mm forks will have Gold Valves.The ignition will be replaced with a modern unit mounted to stock backing plate. We did find a source for the cam chain which is the only hard to find part. The rest of the engine uses water cooled parts that are still available. I'm intersted in any MX 4 speed engines if anyone has one, mine has some bad gears. Long live megaphones!

 

[Michel Dufayard]

Hello pvmx510tc
Do you have pics of the transformations ?
Thanks
Michel

 

[SA63]

What diameter did you make the aluminium push rod?- very interesting. The standard rod has M5 threads and is not particaularly robust, but I would have thought M5 aluminium no good either.
Some photos would be good as Michel said..
Cam chain should be easy to find from any bearing/ chain supplier by the metre (or foot)
My mate here bought a length of it + masterlinks, both using it

 

[ruwfo]

Ok, almost finished swapping all the rear suspension/swingarm/rear brakes stuff over onto the 85 510 frame,(though pics still shows the 430 swingarm), so next i'm looking into make the intake adapter.

By using the CAD system at work i've been able to model 1/1 (dummy up) a crude intake system, so i can see what's what. As you can see from the drawing i created by angling the intake down slightly you gain quite a bit of distance. Though after doing some test fitting
a straight intake spacer & carb mount spigot on my carb, it sort of fits without any angled adapter needed?? . Finally should have time this week to tackle this .

 

[1Tuff500XC]

Real fun project. I've started having thoughts of a twin shock 4T as well. Great info..........

 

[ruwfo]

Here's some new pictures of the project, almost there. I'll post some detail pictures when i get a chance

.

Husky John