AVON Seajet, Yamaha 63N / 62T, J700G engine jetrib Guide

[vas]

hi all,

seen Jeremy's williams jetrib guide and after 4 seasons of sorting out a now 20yo Avon jetrib, I decided to write down a maintenance to do (and how to) list of issues I had to address to keep a well maintained 20yo seawater jetrib in reasonable and reliable condition. Any corrections, additions, comments welcomed!

First of all, a couple of links that will help identify parts or understand how the thing works!
1999 Yamaha WAVE RUNNER XL700 (XL700X) OEM Parts, Flemington Yamaha [describes all subassemblies and part numbers]
Yamaha Watercraft Service Manuals PDF [lots of manuals, WaveRunner XL700 fits the bill, others as well…]
http://fos.prd.uth.gr/vas/crafts/var/Avon320-400DL2t.pdf is Vol2. Technical Specifications-Assembly procedure for the Seasport Deluxe Jet 320 & 400. That’s the steering wheel version jetski of same age. I do have my manual but it’s paper and v.hard to scan/pdf it without destroying it so not so keen. Most things are identical, service, operation, etc procedures are common, so a good read.
DISCLAIMER: anyone spent years on two stroke marine engines will find some of the following boring, apologies, I’m simply trying to show the whole process!

IGNITION:
That’s the simplest of all, replace plugs, check you have spark, do nothing if spark is good. Unless rib is flooded with tons of seawater staying in for lots of time, engine and front cover (where vital ignition bits live) will be still sealed nicely and working fine. Same applies for the black box with the actual el. Ignition unit and starter relay. However, if for some reason you need/have to remove the 250X100X60mm black box, remove the seat AND THE FUEL TANK, before you can get a socket in the two holes back there to undo the two screws holding it in place. On replacing, fit two longer M8 (iirc) hex bolts with nuts on the black box side and second washer/nut combo to keep the box in place. Next time you want to remove the box, it’s a matter of two nuts and it’s off. Not sure why they did it like that, but wasn’t smart!

FUELING:
I’d highly recommend getting 2X service kits for the MIKUNI SBN carbs. Two cylinders, two kits. A couple of links on how to dismantle and replace all vital bits on them:
Mikuni Keihin Carburetor Rebuild pt.1 [by Andrew Sands]

Mikuni Keihin Carburetor Rebuild pt.2 [by Andrew Sands]

Relatively easy job, needs a bit of care and kindness not to damage anything. Only two inner screws were a bit tough to remove, all else straight forward. If membranes/seals/whatever were never changed on yours, I’d be v. impressed if it doesn’t have some serious amounts of deposits and muck around. Don’t forget there’s no fuel pump on these two stroke motors, a pulsating membrane does the job inside the carbs, so vital to have it working fine. WARNING: check the return outlet from the second carb back to the tank. Mine was blocked after having the fuel drained for almost a year. Took a pressure hose to back flush it (part removed from carb obviously) before I could get the carbs to prime with fuel and the engine to fire!
[from Jet Ski Centre Mikuni SBN 38/44/46 Carburetor Repair Kit approx... 80euro, 3-4h job rebuilding the carbs and if you’re fast fitting them back in place J ]
These carbs have chokes and these Yamaha engines are notorious for not starting easily from cold and spending lots of time cranking. Solution is scrapping the chokes and fitting a priming kit easily sourced from jetski places. Basically replace the choke pull button on dash with a similar sized thing which is a tiny fuel pump, connected to the fuel line, remove the chokes from the top of the carbs and replace with tiny jets which pump some fuel instead straight in the carb body. Sounds simple, is simple and does wonders for cold starting! Obviously best done together with the carb rebuilt above
[Jet Ski Centre again, Mikuni Primer Kit -Options: Size: Dual, 30euro, 1h job]
Fuel tank has a 3 level sender with three 1in long areas where three individual floats (with integrated ring magnets) are moving. This matches the four dashes on the righthand side of the dash multidisplay. Mine was flashing in a random manner. Removed the sender – WARNING this means remove the whole bloody ali 40lt fuel tank which is a tight fit under the rear seat, not impossible but needs two persons to do (6screws holding it down) and undo a circlip on a circa 2in rubber cover. Now, you’ll probably find that the floaty material on the lowest or lower two floats has disintegrated due to living in fuel for the last 20yrs or so J. You can try to fix that (magnets are still there!) For example I guess you could use cork from wine bottles with a 9-10mm hole drilled in and a slot to slide the magnet in before putting it on the shaft again, or you can cut from some other material and form some floats. Note that the point where the magnet “closes circuit” so to speak is not at the top of the 1in travel but slightly (3-5mm below). FWIW, Standex Meder MS02-NBR (or PA or -PP) magnetic floats can be used. Problem is tracing them, as none seems to stock them. You want size 2 float which is approximately 25mm outside diameter, 9.1mm inside diameter and approx. 16mm height. Even if you do find them seems that minimum order is 80 or 100 pieces, good luck with the rest ?.
Due to the above, I ended up designing and fabricating new floats from a petrol resistant filament in the local 3Dprinting facility. Made them thin walled and obviously hollow to keep weight down. Works a treat although I had to go up in diameter and height to get enough volume for the thing to float, made a few extra just in case, if you want any give me a shout! BTW, make sure you put them the right way up with the magnet up.
Before embarking in a repairing job, make sure that the values with the respective magnets in the UP position, using a digital ammeter, are as follows:
Empty (all floats down): 667-713 Ohms
1/3 (bottom float up): 292-308 Ohms
2/3 (bottom and mid floats up): 97-103 Ohms
3/3 (all three floats up): 0-2 Ohms
Obviously check the fuel hoses from tank to carb in and return and replace the inline fuel filter with a new good quality one.
[s/h sender from the US for 50-60usd, or contact me for floats!]
There’s a similar setup for the oil level, haven’t touched it, bet the above apply there as well.

BODY/HULL:
There are four latches inside the superstructure once you undo them you can undo the oil filler hose (two circlips), the ON/OFF switch red cables and flip the whole thing towards the bow, giving ample space to work on the engine and paraphernalia.
Had enough to do with the other subassemblies, that tbh haven’t done anything on the hull. Didn’t need to though. Do plan to insulate the thing as it’s too noisy for my liking with some foil lined sound panels I got off the generator soundbox that I have scrapped. Exhaust box under the rear seat and fuel tank produces most of the metallic annoying 2T noise of the whole rib, easy to stuff and quieten I recon.
Regarding the tubes, it looks like the internal baffles have become detached (at least partially) so when I fill with air on one valve, the lot inflates. Not too bothered, what I’d like to know is if the tubes are pvc or hypalon, it’s quite unclear in the manual, none seems to know.

[to be continued as I hit the 10k character limit...]

 

[vas]

[part 2]

ENGINE:
Yamaha have approx. 1 gazillion engine models, that’s a fact. Another fact is that you wont ever find a single bloody screw if you start searching on google/ebay using keywords like: “AVON JETRIB YAMAHA engine” whatever, just forget it.
Engine is 700cc, 2cyl, 2stroke, 2MIKUNI carbs, el. Ignition thing, built around 2000 (mine is 10/2000). So look for spares for Waverunners & Waveraiders, built around 96-97.
Have a look at the link on top of the post for all the engine bits and bobs – skip the body parts obviously!
Flushing the engine with fresh water after each use (yeah right) is a must. If not, make sure you flush for a 10min minimum once out of the water. I try to do it once I’m back from a 1 week long outing.
Out of curiosity and having removed the engine anyway this winter, I removed the cylinder head to have a look inside. There was some salt deposits but nothing exceptionally bad, I could skip removing it, and tbh wont bother again I think. I guess a bit of redlyme could do once you figure a way to recycle it which means rib on a trailer, BIG bucket under the jet outlet to gather all liquid, small pump and hose dipped into the bucket and back into the inlet.
Need a cylinder head gasket and a block to cylinder gasket to complete the repair. I reused the exhaust and inlet gaskets, could replace them, didn’t have time to wait for the spares to arrive in Athens main Yamaha dealer. Mind cylinder head and other engine gaskets are same for ALL 700cc 2cyl 2T jetski engines, don’t bother mentioning Avon to them, you’ll just confuse them…
[two gaskets 60euro, guess if you replaced all top ones would be around 100-120euro]
Anyway, main and ONLY issue I had was salt “eaten” exhaust. I’m talking about the Muffler2 (horizontal part with the YAMAHA embossed in it) and the outer and inner cover exhaust (bolts on the Muffler2 and exhaust flexhose fits on the other side). Seriously rotten and eventually after some shaking about, two pieces around 20X60mm fell off This meant that at the first trip after the carbs rebuilt all cooling seawater ended up in the bilge and after a 10min drive I almost ended with a flooded rib Conveniently the corrosion is at the bottom of the middle exhaust section and cannot be spotted by just looking around the engine. Tried repairing/welding the exhaust, no luck, it’s a fancy (and most likely) magnesium alloy cast, v. difficult to impossible to weld. For last year I ended up epoxying (and blocking) part of the waterways around the exhaust. Rib worked, not v. well though (but most likely due to wrong carbs tuning). This winter I got a s/h full exhaust from a freshwater jetski from some US lake, was spotless!
Now a few warnings! Before buying an exhaust, please remove yours (or check my pics) and make sure the outer/inner cover exhaust has the right orientation for the exhaust flexhose, some have an outlet much more horizontal, may work, don’t know. Note that some exhausts don’t have a bypass inlet next to the exhaust hose, don’t worry and scrap the tee and hose, still works fine. Don’t even bother removing the two lower parts of the exhaust, they are clean for sure and a hassle to remove just to look at them and refit! You only need to remove examine and most likely replace the two final pieces of the muffler. Do check the rubber boot and the inner silicon exhaust joint inside it. Rubber boot slides down towards the exhaust manifold leaving space to do and undo the circlips sealing the exhaust gasses passing to the muffler2. Sorry complicated typing all that, easy once you take it apart carefully.
Original exhaust boot between the exhaust elbow and exhaust muffler2 has an outlet for the peeing tell-tale hole on the stbrd side of the stern. You can scrap it all together if you wish (don’t find scrapping the only way to know there’s indeed cooling water through the engine v. wise though!), or keep the original boot, or use it at the tee that used to go to the bypass inlet next to the exhaust hose. Note that the tell-tale outlet does get clogged with salts, undo from the engine side, and back flash with a high pressure air hose from the stern and then you’re sure it works fine. Doesn’t pee at idle speeds (at least mine doesn’t) but once you rev it up it will!
[s/h exhaust circa 200euro I think you can get the section you want new for 500-600euro a piece- most likely you want both pieces so a grand for exhaust is a bit steep! first time you do it probably a few hours]
Experienced jetskiers insist that I should scrap the oilpump (tiny device mounted on the front of the engine) and mix fuel/oil in the tank directly as the small hoses may/will fail and then kill your engine from oil starvation. May do, not sure and not yet as I’m not keen having carb jets full of oily fuel standing there. Now oil just goes straight in the cylinders from tiny jets mounted on the plate bolted on top of the carbs and were the flame arrestor and filterbox bolt to. I guess I could add a fuel cut off valve next to the filter so run the engine till the carbs empty when flushing with freshwater and avoid the drying oil in the carb issues, we’ll see. Would be keen to have a solution to the oil cloud it leaves behind at idle and warming up, not sure the readymix will do that tbh.

ELECTRICS:
AVON seem to have sourced a few things from PERKO, a US el. co. Jetrib has a red/green nav light which sits WAY TOO proud on the bow. The plastic transluscent/white assembly was slightly broken from the mount underneath (which bolts securely on the tube below and where the two wires are coming again through a double skinned bit of tubing – sorry difficult to explain, easy once you remove the Philips screw that holds it down to the base. On the first outing with the rib on the bathing platform and stern to mooring on a port with decent swell, I lost the red/green plastic cover from the sternlines of the boat next to me fouling on the rib bow… Currently in the process of designing and 3D printing a new low profile lid that fits on the existing base.
[PERKO 0252WB0DP1 red/green nav light assembly is 45usd]
Rib also has a stern mounted all round (amazingly it’s led!) Both work from a rocker switch on the dash. Just needs a good clean of the two contacts.
There’s also a PERKO ON/OFF-LOCK big red switch with a key under the seat. Works fine, PO didn’t have the key, found a company in the US who does them and got one based on the number stamped on the keyhole surround. Check with them if you want one, v.helpful!
PERKO Inc. - Catalog - Battery Switches - Medium Duty Main Battery Disconnect Switch with Key Lock [9602]
Check with these guys: Lost A Key (my quote mentions Key for Delta Hurd Knaack Perko GM Lowe's (0) cannot find it though now, so just ask with this)
[PERKO ON/OFF-LOCK key 8USD + 15shipping…]
There’s also a second switch on the dash which runs a 75mm dia bilge extractor fan which should be run before each engine start. Mine was stuck solid, 15euro bought me a new one. Lives at the front of the bilge in front and almost under the engine which is the right spot as petrol fumes are heavier than air and gather at the bilge and almost a certain way to kill it once the bilge fills with seawater… Also easy to forget the switch pressed and if switch is ON kill the tiny battery. Amazingly I’m still on the battery that I got the rib with 4yrs ago. Two stroke low compression helps I guess J
Final issue is the dash multidisplay. My display is too weak, bars flashing, not really legible in the med sun and most important has a dark (well black) vignette at the lower section. I removed it to have a look, no luck it’s a sealed unit with 100-150mm cables at the back with sockets on them! There are a few s/h on ebay but north of 250usd. Winter plan is to remove it again, dremel it open from the back and have a look inside before that I’ll make sure the voltage it gets is within specs and start connecting subassemblies to test it (Ohm pot for fuel/oil level). TBH, except for speed that does sort of work, I’m only keen on fuel level (run out of fuel last year twice) and engine hours. BTW, there’s no rev counter (would be nice for checking purposes). There are three indicators for oil level, high temp and fuel level, the level ones flash together with the lower dash on the respective gauge when empty. I’m afraid that the LCD is dead though and the only solution is another s/h one. Final warning on the multidisplay is that there are a few variants of the thing, so if you’re sure yours dead (and it’s not a voltage supply issue!), remove it, and compare the sockets at the 4cables off the dash to the ones on sale, some have only 3, no idea what they are missing but surely wont be good for yours…
There is only one sensor in the whole engine and it’s on the cylinder head for temperature. No gauge, so it’s a simple on/off temp switch that lights the mid indicator on dash. Cannot possibly do anything more complex like getting engine in limp mode or something as there’s no ECU on the thing!
[s/h multidisplay 250+ + shipping+tax, circa 400euro, not cheap!]
Simple machines, if they start, idle with a smoke cloud at the back, plane instantly (and scarily) with no smoke cloud at the back and pee water at the back, they should be fine

[to be continued!]

 

[vas]

[part 3]

CONTROLS:
There are two Teleflex controls, one for steering and one for forward / neutral / reverse. After twenty years and not knowing if they are the originals (I v.much doubt it tbh) they were both v.hard and each year needed a lot of persuasion (and WD40) to start shifting again…
The forward/reverse was the worse of the two, so having taken everything apart was a great opportunity to replace it. Was a standard 9ft Teleflex item, half an hour job to do with engine and tank off. You MUST take the tank off, you don’t have to remove the engine though…
Another issue specific to the fwd/reverse is that I could not get out of reverse and into neutral with the engine running in the water. Fine when engine turned off or running on the hose off the water, ended up in maneuvering to killing the engine, get it back to neutral, start the engine, continue. Puzzled a bit realized that there’s a smallish “gate” where the flap coming down over the jet to get into reverse which basically holds the flap into reverse once you rev the engine a bit. Difficult to explain again, have a look it will be relatively (?) obvious – it’s also on the manual. At first I started by lowering idle speed by the ear as there’s no rev counter on the thing (mind it’s easy to get a high idle especially after rebuilding the carbs!) and then checked on the manual which has a special section on regulating this Teleflex. Followed the instructions (turn steering to port and lever to reverse), got the gap up to 2mm (was pressing hard against instead of not touching the end of the gate…). Same thing unfortunately. So I started tightening the Teleflex on both sides so that the reverse action doesn’t push the cover over the jet too far down. After the third attempt it worked and now my reverse is weaker than before but reversible so to speak J
Steering Teleflex is a bit more difficult to replace still doable with tank off only. You can skip that by making sure you oil them properly at the end of the season (both ends!) and if stuck next season wedge a 4x4in bit of log 1m long in the jet end and slowly start moving it left and right. Don’t try and stress the handles, you’ll most likely damage them!
Accelerator is a normal push bike flex, never had a problem with it and hence haven’t bothered messing with it.
[gear Teleflex circa 20euro]

That’s it basically!

cheers

V.

 

[MrB]

Sweet, nice job Vas.

 

[Sparkyr6]

[part 3]

CONTROLS:
There are two Teleflex controls, one for steering and one for forward / neutral / reverse. After twenty years and not knowing if they are the originals (I v.much doubt it tbh) they were both v.hard and each year needed a lot of persuasion (and WD40) to start shifting again…
The forward/reverse was the worse of the two, so having taken everything apart was a great opportunity to replace it. Was a standard 9ft Teleflex item, half an hour job to do with engine and tank off. You MUST take the tank off, you don’t have to remove the engine though…
Another issue specific to the fwd/reverse is that I could not get out of reverse and into neutral with the engine running in the water. Fine when engine turned off or running on the hose off the water, ended up in maneuvering to killing the engine, get it back to neutral, start the engine, continue. Puzzled a bit realized that there’s a smallish “gate” where the flap coming down over the jet to get into reverse which basically holds the flap into reverse once you rev the engine a bit. Difficult to explain again, have a look it will be relatively (?) obvious – it’s also on the manual. At first I started by lowering idle speed by the ear as there’s no rev counter on the thing (mind it’s easy to get a high idle especially after rebuilding the carbs!) and then checked on the manual which has a special section on regulating this Teleflex. Followed the instructions (turn steering to port and lever to reverse), got the gap up to 2mm (was pressing hard against instead of not touching the end of the gate…). Same thing unfortunately. So I started tightening the Teleflex on both sides so that the reverse action doesn’t push the cover over the jet too far down. After the third attempt it worked and now my reverse is weaker than before but reversible so to speak J
Steering Teleflex is a bit more difficult to replace still doable with tank off only. You can skip that by making sure you oil them properly at the end of the season (both ends!) and if stuck next season wedge a 4x4in bit of log 1m long in the jet end and slowly start moving it left and right. Don’t try and stress the handles, you’ll most likely damage them!
Accelerator is a normal push bike flex, never had a problem with it and hence haven’t bothered messing with it.
[gear Teleflex circa 20euro]

That’s it basically!

cheers

V.

Wow what a great write up