Re: Meddling with a Wisp

Just saw first and last pictures, nice work. All mobys ive had were smooth except when the mounts go out then its a jerky shaky thing. Id weld up some engine mounts n that springy hook thing. Or start balancing stuff magneto pulleys etc. Amazing how much energy lost to vibration instead of smoooothness.

Re: Meddling with a Wisp

Is it possible to isolate the upper mounts with rubber, a bushing, maybe something like what is used on the Model "7"? It would be extreme but I suppose one could "balance" and blueprint the engine? But$$$$.

Re: Meddling with a Wisp

> pat splat Wrote:

> -------------------------------------------------------

> Just saw first and last pictures, nice work. All mobys ive had were

> smooth except when the mounts go out then its a jerky shaky thing. Id

> weld up some engine mounts n that springy hook thing. Or start

> balancing stuff magneto pulleys etc. Amazing how much energy lost to

> vibration instead of smoooothness

Cheers Pat, I'm probably being thick here but you lost me on "that springy hook thing"?

Good shout on balancing the external bits, hadn't thought of it but if the pulley is out that could cause serious vibration.

> Stephen Keller Wrote:

> -------------------------------------------------------

> Is it possible to isolate the upper mounts with rubber, a bushing, maybe

> something like what is used on the Model "7"? It would be extreme but I

> suppose one could "balance" and blueprint the engine? But$$$$.

Cheers Stephen, I'll pop these guys out and see what space I have to play with, iirc they're 6mm thick.

20200923_122144.jpg

Any clue what rubber would hold up to that kind of heat?

As for engine balancing, I think that might be too overboard.....its only mopeds right? And can you really balance a single anyway?

Re: Meddling with a Wisp

The “springy hook thing” is the engine tensioner that variated moby engines use in place of that rear mount that you have. I don’t think the poster of that comment read through the whole thread.

Re: Meddling with a Wisp

You could buy some ductile butyl rubber and mold it around the head mount bolt. Slide it into the head then use a chopstick or somthing to cram the rubber in tight. Then bake at 350 for a while to vulcanize it. Boom custom fit rubber isolator

I'm almost certain it was butyl....we used to fool around with in school, then vulcanize the parts in an oven....you could work it like clay

Re: Meddling with a Wisp

> Mike Boyd Wrote:

> -------------------------------------------------------

> The “springy hook thing” is the engine tensioner that variated moby

> engines use in place of that rear mount that you have. I don’t think the

> poster of that comment read through the whole thread.

Ah, now it makes sense, cheers Mike. I would love to have that type of mounting and run a variator, but I'd have to mod the frame and I don't want to do that.

> Aaron Blair Wrote:

> -------------------------------------------------------

> You could buy some ductile butyl rubber and mold it around the head

> mount bolt. Slide it into the head then use a chopstick or somthing to

> cram the rubber in tight. Then bake at 350 for a while to vulcanize it.

> Boom custom fit rubber isolator

>

> I'm almost certain it was butyl....we used to fool around with in

> school, then vulcanize the parts in an oven....you could work it like

> clay

Love it Aaron, that sounds like a perfect solution! Never played around with butyl but well up for having a go.

Re: Meddling with a Wisp

Ok, so decomp is useless when it comes to plug chops, lesson learnt but at a cost of a soft seize 😢. Shoved an endoscope down the plug hole and there are some marks on the bore, won't know more til I pull it to bits. Soft seized at full chat so I'm OK down low but lean at wot, before really pushing it further I'll take up the offer I've had to put it on a dyno and dial it in exactly.

Question tho. I'm new to all this, is it OK to keep a 2 stroke engine pinned if you've got it jetted right??? I'm running a bit retarded (but people have said that for years) so I thought I'd be on the safe side. Any help guys and gals would be appreciated, digging for your wisdom here, how do you roll at wot? Let off and back on or never push right to the limit, I know it's the most newb question to ask🤦‍♂️

Re: Meddling with a Wisp

> Tom Boyd Wrote:

> -------------------------------------------------------

> Ok, so decomp is useless when it comes to plug chops, lesson learnt but

> at a cost of a soft seize 😢. Shoved an endoscope down the plug hole and

> there are some marks on the bore, won't know more til I pull it to bits.

> Soft seized at full chat so I'm OK down low but lean at wot, before

> really pushing it further I'll take up the offer I've had to put it on a

> dyno and dial it in exactly.

>

> Question tho. I'm new to all this, is it OK to keep a 2 stroke engine

> pinned if you've got it jetted right??? I'm running a bit retarded (but

> people have said that for years) so I thought I'd be on the safe side.

> Any help guys and gals would be appreciated, digging for your wisdom

> here, how do you roll at wot? Let off and back on or never push right to

> the limit, I know it's the most newb question to ask🤦‍♂️

If it's jetted rich enough , you should be able to hold WOT for miles with no ill effects . Just don't close the throttle after WOT going down a hill or lengthy WOT run . Ease it down .

I run my FA50 full throttle for miles before slowing for a turn .

Re: Meddling with a Wisp

Yeah getting that SHA dialed in so it can idle nice and lean but be rich enough at the top with a smooth delivery curve is the key. Have you already opened up the upper hole in the brass tube?

One thing that could also help is ensuring a stable pocket of air that the carb is drawing from at all speeds. Helps make the carb more consistent at all ranges. Since the engine doesn't pivot like most Mobys you could potentially fabricate an air box inside the frame behind the carb. There are formulas you can search for that estimate the ideal volume based on bore size etc.

Re: Meddling with a Wisp

> P D Wrote:

> -------------------------------------------------------

>

> If it's jetted rich enough , you should be able to hold WOT for miles

> with no ill effects  . Just don't close the throttle after WOT going

> down a hill or lengthy WOT run . Ease it down .

>

> I run my FA50 full throttle for miles before slowing for a turn .

Thanks for the advice PD, thats good to know, the thought occurred to me after watching this:-

Made me realise just what's happening in there when flat out and how much heat is being generated, skip to 6:39 and have a gander.

Re: Meddling with a Wisp

> Mike Boyd Wrote:

> -------------------------------------------------------

> Yeah getting that SHA dialed in so it can idle nice and lean but be rich

> enough at the top with a smooth delivery curve is the key. Have you

> already opened up the upper hole in the brass tube?

Thanks Mike but no I haven't, tbh I'd completely forgotten about that bit🤦. Guess I should order some jet drills sharpish, what sort of range should I be looking for, and it'd be great if you could suggest a starting point (did search but didn't find much)?

>Mike Boyd Wrote:

> -------------------------------------------------------

> One thing that could also help is ensuring a stable pocket of air that

> the carb is drawing from at all speeds. Helps make the carb more

> consistent at all ranges. Since the engine doesn't pivot like most Mobys

> you could potentially fabricate an air box inside the frame behind the

> carb. There are formulas you can search for that estimate the ideal

> volume based on bore size etc.

I had a similar thought, I was thinking about whether I could make up a version of a JBOT bottle. Space is a tight with these gusset plates and to put the belt on you pull the engine back so far that the filter hits the plates.

20201007_150453.jpg

The air should be pretty stable there, the chain cover completely covers the filter, I might try and work something out but so far I've drawn a blank. (edited)

Re: Meddling with a Wisp

A friend of a friend has offered up some dyno time to get the carb dialed in and see what humongous power the engine is producing. I mean why wouldn't you take up the offer.....its mopeds right!

20210915_113736.jpg

I think I've got all the bits I need, hopefully I won't need to drill out the atomiser tube and I can get it running right just through jetting but I got some drills just in case. (edited)

Re: Meddling with a Wisp

Sha tuning is easy just keep in mind that rather than going down a jet you can remove a screen from the filter pack and add some more air to the mix. And always jet for top speeds. You might end up a little muddy at the bottom but you wont seize at your top.

Re: Meddling with a Wisp

Those white wall tyres turned out to be properly shite, sidewalls cracking really badly after less than a year. Blessing in disguise as I found a few of the rear spokes were a bit loose. I asked a friend who works on push bikes to relace them and he suggested going stainless and up a spoke gauge, well he did a cracking job (I did some jobs for him so ended up just paying for the spokes)

20220422_143421.jpg

Then I started hunting for better tyres and I found some BMX tyres are the same size, take 65psi, reinforced sidewalls and fatter to boot. I was using 16x1.25 and found these bad boys 16x2.3, not sure about the Vans waffle cut tread but they're super low key.

20220425_122058.jpg

They only just fit in the forks and it handles a lot better than it did before. I bought them as a bit of a joke, thought it would looks completely ridiculous but I actually quite like em.

20220425_122120.jpg

Re: Meddling with a Wisp

Looks rad! Have you considered fabbing up a little rectangular cable management doohickey, maybe from that mounting point for the crossbar? It’s tough with tall bars like that but I think a little cinch there could clean up the look while still allowing full range of movement

Re: Meddling with a Wisp

Honestly if both sides of cables got cinched to their respective side of the bottoms of those bars it would manage them and definitely allow the full range of movement needed. Just allow them to have a little bit of a loop out from the top of the bars where they go into the controls.

Looks funky man and I love it!

Re: Meddling with a Wisp

Thanks guys! I did try feeding the cables through the little light bracket at the bottom of the bars but it didn't look right. Hadn't thought of making something to cinch them to the lh and rh of the bars, I'll have a play around 🤔.

Also old tyres were 16x2.125 not 1.25. New tyres have geared it up a bit but don't have a GPS speed, I had finally found a 36t rear sprocket to replace the 38t but I'll hold fire at the moment.

If anyone else is stuck, puch maxi sprockets are an exact fit, you just have to space them off the hub a bit to miss the spokes, the time I've wasted looking for a nos wisp sprocket...

I took it for a run this afternoon and it's running great, flying through some twisty country lanes, should have been paying more attention to the temps as it nipped slightly (181°c / 358°f). I'll upjet to a 76 and try that🤷.

Re: Meddling with a Wisp

Threw a 76 in there this avo and went for a spin, there's a nice 7.5 mile run round work that has a great flat straight half the way round. Air temp. 4°c lower than yesterday, top speed 39.2mph (gps) but head temps reached 183°c (didn't nip tho) so I limped it back after that. Didn't feel as fast as yesterday but that might be because it was less lean. I'm going to go round it again and check for air leaks, kinda expected a drop in temps today, sooo close to the 40 barrier.

Any thoughts on whether to try the 36t sprocket? I'm wondering if I raised the gearing it might not rev out to the point where temps keep climbing, or keep as is and continue to up jet?

Been having a think about cable routing and I think I've hatched a plan, just need some spare hrs now.

Re: Meddling with a Wisp

Hmm it shouldn't be seizing at those temps, sounds like you might need to back off your timing a bit. If going richer doesn't bring the temp down, it's not your problem. Turn whatever knob makes the biggest difference.

An air leak, while possible, seems unlikely based on the fact that your build quality is excellent and the larger jet didn't immediately make a difference, you could keep going bigger and see what it does but if the timing too advanced, no matter how rich your piston will still be hot and seize

Re: Meddling with a Wisp

Get the smaller sprocket on there it may help keep your rpms a little lower and help with temps. You will gain a little on the top end too. But might lose some take off oomf.

Re: Meddling with a Wisp

Thanks for the advice, I'll try retarding the timing back a bit first and then change the sprocket, that way I'll know which makes the most difference.

Re: Meddling with a Wisp

Usually higher load= higher temp, unless its more or less getting into the pipe, taller gears and more load on the engine even though the rpm is lower, will be hotter. Higher rpm is actually moving more air through the engine so it should run cooler, but practically speaking who knows.

It sounds like your problem is unrelated to jetting or gearing, if timing can't help you, you will need to look at the head design or possibly even the exhaust

Re: Meddling with a Wisp

Cheers Graham, that makes sense, I'll try timing and a serious diet then.

Re: Meddling with a Wisp

Thought of another variable I'd neglected to consider.

Couldn't get E5 recently due to some environmentalists slashing truck tyres 😒 so I'd got a few litres of E10, drained the tank today and fresh E5 back in. With no other changes head temp. maintained  173°c for the whole 7½ mile loop @ sustained wot, even though ambient temperature was 10°c higher than my last test run. I had heard E10 ran hotter but I never thought it would make such a difference, did pink once or twice (weirdly at 145°c starting the run) so I'll still back the timing off a bit.

Re: Meddling with a Wisp

Could someone school me on what they think might be going on here👇.

I'm still trying to tune my ear into 2t engines, sounds like it might be 4 stroking but the plug chops look on the lean side. This was a warm up run so engine is still cold (100°c) and lambda sensor crapped out so testing was aborted.

9:1 compression

Ngk BR6HS

16:16 dellorto (full mesh filter) 76 jet

40:1 E5

Timed 19° btdc

I'd like to get it running better before I try this again, any help/advice/pointers would be greatly appreciated!

Re: Meddling with a Wisp

Just read this from start to finish, excellent work! A guy on my brother-in-laws estate has a Wisp and it looks sketchy at best, so cap doffed for bravery too.

Iain in always sunny Lancashire.

Re: Meddling with a Wisp

> I M wrote:

> -------------------------------------------------------

> Just read this from start to finish, excellent work! A guy on my

> brother-in-laws estate has a Wisp and it looks sketchy at best, so cap

> doffed for bravery too.

>

> Iain in always sunny Lancashire.

Cheers Iain! Sketchy is pretty generous, hand signals are out of the question, instead I point with my legs🤣. If you ever get chatting to your brother-in-laws neighbour, advise changing to BMX tyres, the difference is amazing!

Nice to hear from another UK mopeder👍, are you part of the Lancashire slow riders?

Re: Meddling with a Wisp

I would just try going up in jets until you make that plug nice and rich, then back off one.

Re: Meddling with a Wisp

> Tom Boyd wrote:

> -------------------------------------------------------

>Cheers Iain! Sketchy is pretty generous, hand signals are out of the

> question, instead I point with my legs🤣. If you ever get chatting to

> your brother-in-laws neighbour, advise changing to BMX tyres, the

> difference is amazing!

>

> Nice to hear from another UK mopeder👍, are you part of the Lancashire

> slow riders?

NO, and I'm moped free. always had one on the go though as a rule. Last one was a Tomos and before that a Honda PC50 which I had for donkeys years. Also had a Vespa Ciao and a couple of Yamaha geared 'peds.

Re: Meddling with a Wisp

> Jay Rivett wrote:

> -------------------------------------------------------

> I would just try going up in jets until you make that plug nice and

> rich, then back off one.

I was running a 76, tried a 74 and it felt lean, went up to 78 and it was boggy and unrideable. I'll order a 75 and 77 now I know roughly where I'm at.

Also i think that noise in the video might be points flutter🤔, I checked them and they are gapped at 12tho, how tight can you gap points?

Want to post in this forum? We'd love to have you join the discussion, but first:

Login or Create Account