Gas Gas Trials bike conversion

General Discussion about large electric scooters and motorcycles and other things with no pedals.
bigpie   100 mW

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Gas Gas Trials bike conversion

Post by bigpie » Jun 23 2017 4:04am

Hi,

I'm looking to convert an old Gas Gas 250 2 smoke to electric. I'm not sure what motors would be good to start looking at. I did think one of the QS hub motors for easy of conversion, but I'd not be able to play with gear ratios if I needed to.

What motors should I be looking at?

With trials riding its all about slow speed, technical riding. Response needs to be punchy, top speed need not be over 25/30mph. Range won't need to be much. I was thinking 48V 15/20 AH hobby lipo and have a couple of swappable packs.

Heat build up shouldn't be much of an issue, more time spent walking the sections than riding them.

Not my bike, but it look pretty much like this
Image

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Re: Gas Gas Trials bike conversion

Post by bigpie » Jun 23 2017 5:30am


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macribs   1 GW

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Re: Gas Gas Trials bike conversion

Post by macribs » Jun 23 2017 7:33pm

Could you fint a common qs 205 dd hub motor as a mid drive mounted in the frame? Then you can do only one step down via sprockets and chain and still have a lot of torque to jump rock walls, containers and whatever else you trial freaks jump. If motor fills up the frame maybe you can do back pack battery? Will for sure make it easy to sway out a used pack for a fresh one. You will have all mass centralized so you can still use stock wheel at the back.

bigpie   100 mW

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Re: Gas Gas Trials bike conversion

Post by bigpie » Jun 29 2017 9:25am

thinking of going for a 3kw golden motor now, not sure if to go 48v or 72v

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Re: Gas Gas Trials bike conversion

Post by Ianhill » Jun 29 2017 11:07am

bigpie wrote:thinking of going for a 3kw golden motor now, not sure if to go 48v or 72v
Good choice of motor, go for 48v i would on a trails bike and feed it lots of amps it should be slow but powerful.
My 1000 post too :)

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DanGT86   10 kW

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Re: Gas Gas Trials bike conversion

Post by DanGT86 » Jul 13 2017 12:20pm

What is your budget? What is the original HP of the bike? That's a good place to start your planning.

I would not use a hub motor in the wheel. You want as light weight of a hub as you can get. The suspension has no ability to absorb the impacts between the rim and the hub so an in wheel motor would be terrible in this application in my opinion. Low speed with no airflow is the worst possible scenario for a hub motor or really any low RPM motor. If you do end up going mid-drive you should try to position the final drive sprocket as close as possible to the location it was on the gas bike. The interactions between the suspension and the chain pull force are engineered into the bike and should be maintained if you want it to be comparable to the original bike.

You want the motor to spin fast. RPM makes motors happy. If you run a cooling fan on the motor then the high RPM of the motor can move lots of air over it when the bike is barely moving.

A Lightning Rods big block might be a good place to start. Really just depends on your desired power level. Some people have installed small RC motors in the crankcase of 2 strokes such that the original transmission is retained. This might be a good idea in your case but unfortunately RC drives capable of stock trials bike power are expensive.

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sn0wchyld   1 MW

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Re: Gas Gas Trials bike conversion

Post by sn0wchyld » Jul 17 2017 10:06pm

theres a couple of larger motors from cyclone.tw that might fit the bill - there like a big block version of LR's big blocks, rated at 7.5 and 18kw, and weighing about 10kg and ??kg respectively (i dont know the weight of the 2nd)
a small but high C rate battery and a decent controller could make for a light but very torquey setup.

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Re: Gas Gas Trials bike conversion

Post by bigpie » Jul 18 2017 2:12am

I'm hoping to keep it under £1000.

I've not really made much progress yet, I've become distracted putting a motor on a skateboard for my lad.

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macribs   1 GW

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Re: Gas Gas Trials bike conversion

Post by macribs » Jul 18 2017 9:17am

That 7.5 kw cont/18 kw peak cyclone what do you reckon is real world power for that motor? If you see at least 12-15 kw that should give you the power needed to climb rocks, containers, and other crazy vertical stuff you find.

Imagine a clutch casing and hooking the high powered cyclone up to a clutch and you could ride it in true trial style with throttle control and a lot of clutch for fast take offs like when launching the bike into a vertical climb.

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DanGT86   10 kW

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Re: Gas Gas Trials bike conversion

Post by DanGT86 » Jul 18 2017 9:21am

Trials bikes are generally in the 15-25hp range and around 150lbs. Trying to hit those targets on a budget of 1000 is going to be challenging. On the other hand I bet trials riding doesnt actually require the full power of the gas engine so you could probably have some real low speed fun with 3-5kw assuming it was geared properly.

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Re: Gas Gas Trials bike conversion

Post by Ianhill » Jul 18 2017 9:25am

macribs wrote:That 7.5 kw cont/18 kw peak cyclone what do you reckon is real world power for that motor? If you see at least 12-15 kw that should give you the power needed to climb rocks, containers, and other crazy vertical stuff you find.

Imagine a clutch casing and hooking the high powered cyclone up to a clutch and you could ride it in true trial style with throttle control and a lot of clutch for fast take offs like when launching the bike into a vertical climb.
If efficency ain't your thing you could even add a little weight to the flywheel with the electrics extra torque. And when the clutch drops with a short ratio look out duggie lampkin.

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Re: Gas Gas Trials bike conversion

Post by Ianhill » Jul 18 2017 9:38am

With electric around 3 times more efficent 8kw geared well would compete with high end ice bike's and with the tweeks to the drive train no reason they can't dominate this sport.
For a cheap run around I bet a 1600w brushless motor that I use on my scooter could do the job I've run it at 4kw peaks for over 20 mins super harsh kicking over mountain roads geared to 50mph and averaged 30mph it was hot but with in limits and it still runs to this day, a hall has failed now the motor is around 2 years old and i had it second hand so its done really well, the phases are fine.
One of them motors run at 72v range gives around 7500rpm no load depwnding on model so gear that down you could do it on a budget of £500 using a cheap sunwin controller and lipo I've run the setup for a year and its proven to be good to me not even a bms just balance charge and run a fuse to protect the pack.
Damn my whole scooter comes in at just over £500 and that's with all the brake upgrade battery's controller shunts the lot.

bigpie   100 mW

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Re: Gas Gas Trials bike conversion

Post by bigpie » Jul 29 2017 3:12am

What's your 1600w motor? I barely use any of the power at my level anyway.

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Re: Gas Gas Trials bike conversion

Post by jonnydrive » Jul 31 2017 3:21am

Hi,
choosing the right engine is crucial, thanks to my bed experience with lite powerful outrunner motor, may I suggest to evaluate something with a good copper mass, able to keep a lot of amp without overheat.
Check this out http://kellycontroller.com/mars-0907ete ... -p-29.html (not the direct reference because at this moment the Motenergy site is down).

Also Golden motor are good but, for sure, not the 3kw version. You need at least an engine able to keep 10-15kw as peak power (30-60 seconds of boost). https://www.goldenmotor.com/eCar/HPM72-5000.pdf

Trial ride is, for the most of time, low speed run but its requires a lot of torque, it means that the motor must be able to keep a lot of amp @ low rpm without wasting too much power and overheat.
Higher is the voltage lower is the amp to provides the same amount of watt, if you can choose go to 72v or higher.

Last suggestion: when you choice the motor be careful to the values declared by the seller, for examples Cyclone and Revolt lie about the max power able to keep the engine (verified personally).

Here my personal experience, the frame is for testing purpose, if I will able to find the correct engine-battery-controller setup, I will swap with a trial frame.
https://endless-sphere.com/forums/viewt ... 28&t=86532

Ianhill   100 kW

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Re: Gas Gas Trials bike conversion

Post by Ianhill » Jul 31 2017 9:06am

After reading through the thread, I suggest you run it with power comparable to stock or more to make sure your not balls to the wall the setup I talked of would of been heavily geared and not made 10mph to get the torque needed and the wider rev range would of slowed the torque delivery down meaning with the clutch in full revs and drop it the front wheel would of gone up easy but once in motion a full rev would only get a good jerk then at best but still would of been upto climbing anything without melting the motor and weakening the magnets strength but there is a lot of weight there so if you want good performance directly geared motor and lots of amps on a super low kv motor will do the trick and cost alot more but the final product will shine like a diamond in a goats ass.
Best thing is read like hell on some threads and get to grips with the actual math of it so when you get tons of opinions you can sort the fact from the fiction and work something out in your price range and only you know that good luck with it though what ever route you choose.

bigpie   100 mW

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Re: Gas Gas Trials bike conversion

Post by bigpie » Mar 22 2018 4:56am

Having got side tracked with messing around with my lads oset, I'm ready to pick this back up again.

I'm thinking of going for http://www.eastgem.net/d7500-k-1.html with a 10T front 70T rear single reduction.
With 5 of these https://hobbyking.com/en_us/multistar-h ... -pack.html in series x 2 to swap out.

With this gearing the top speed of around 35mph seems fine. Any thoughts or gotchas I've missed? I am by no means a good rider and usually just plod about with my 6 year old on his Oset.

We're having one last ride this weekend then the noisy smokey engine is coming out.

bigpie   100 mW

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Re: Gas Gas Trials bike conversion

Post by bigpie » Mar 24 2018 4:30pm

I've gone with the Denzel kit, I've asked they send the throttle adaptor in place of the throttle tube. It all looks prewired but theres no contactor or pre charge resistor, I was told by them one wasn't needed but the Kelly manual shows one.

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DanGT86   10 kW

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Re: Gas Gas Trials bike conversion

Post by DanGT86 » Mar 24 2018 8:06pm

Kelly makes lots of controllers capable of way higher output where contactors are common. On a heavy vehicle like a golf cart or a car there would defietely be a contactor. Contactors are also useful in a high voltage aplication where you wouldnt want to handle the high voltage connections frequently in normal use. Larger vehicles also have an accessory battery that runs lights and can be a low voltage (12v) control circuit to actuate the contactor.

On most ebikes its hard to justify the weight of a contactor and an additional 12v battery to control it. Most of us don't run them.

The precharge device is definitely required. You can make a precharge connector easily at your main battery connection or try the anti-spark xt90 connectors.

bigpie   100 mW

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Re: Gas Gas Trials bike conversion

Post by bigpie » Mar 25 2018 3:10am

The xt90 connectors have it built in? The loom has an xt90 connection so it looks like it's taken care of. Looking forward to getting going now.

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DanGT86   10 kW

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Re: Gas Gas Trials bike conversion

Post by DanGT86 » Mar 25 2018 9:00am

Not all the XT90s have it but there are anti-spark versions. They have the green on them like this.
XT90-S_01.jpg
XT90-S_01.jpg (11.72 KiB) Viewed 2312 times
I have not tried them myself so ask around.

Its not too hard to add a precharge resistor to any normal setup. Plugging in a 20 series pack without precharge will definitely destroy your connectors in no time.

As for gotchas you might have missed, the real world current you should expect to draw from multistars has been reported by ES users to be around 4-5c. Apparently the voltage sag gets pretty bad beyond that. They can and will do more and your riding style is going to be very short burst so its probably fine. Like everything else there are no absolute hard limits but a general recommended range.

I'm looking forward to seeing how this all works out for you. I'm still dreaming of a trials bike myself and you are definitely in the same budgetary ballpark I would want to be in with the choice of the Denzel setup.

bigpie   100 mW

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Re: Gas Gas Trials bike conversion

Post by bigpie » Mar 25 2018 3:13pm

Thanks for the info.

The Gas Gas is now a Gas Gasless

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Raisedeyebrows   1 kW

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Re: Gas Gas Trials bike conversion

Post by Raisedeyebrows » Mar 26 2018 11:05am

Watching this one, nice choice of bike! Used to ride an older Honda TL and if I see one I could pick up affordably I'd like to do the same thing you're doing.
Yuba Mundo w/BBSHD
Specialized Hard Rock w/9c clone, statoraid, hubsink
Trek Fuel 90 w/BBSHD
Above all run on 14s4p 52v li-ion
Ecobike folder 36v
Currie Flyer scooter 24v on 24ah of SLA

Every trip made with electric bike is one less car trip, saves money, no toxic fumes, less noise, less impact on roads.

bigpie   100 mW

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Re: Gas Gas Trials bike conversion

Post by bigpie » Apr 01 2018 8:25am

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while I wait for the goodies to arrive I've been fashioning a panel to keep all mud splash to a minimum and going to mount the controller on the other side.

No access to fancy tools, so no fancy water jet cutting or CNC etc.

bigpie   100 mW

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Re: Gas Gas Trials bike conversion

Post by bigpie » Apr 11 2018 10:01am

Almost 3 weeks since ordering and no kit yet, no response from them regarding a tracking number or any more details :(

Ianhill   100 kW

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Re: Gas Gas Trials bike conversion

Post by Ianhill » Apr 11 2018 5:24pm

I was sat on a gas gas 250 the otherday, I give it a kick and a quick blip in the guys garden and I found it a very light bike, it fitted my body frame of 6ft perfect when I'm upright i could get some good pops and lean back into a back brake manual it's a very easy bike to ride feels natural and instinctive almost.

If you keep the basic recipe of less is more and the weight is low and torque high you may just have a monster on your hands, i look forward to seeing this one get going and hope you have some success with your parts soon.

Can you press grove's or luvers into the front cover you have made to add a bit of strength ?
There's loads of ghetto ways of adding luvers etc to metal on YouTube, The panel rigidity does increase a fair bit specially if they are done in horizontal and vertical directions combined.

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